[SPARK-2627] [PySpark] have the build enforce PEP 8 automatically

As described in [SPARK-2627](https://issues.apache.org/jira/browse/SPARK-2627), we'd like Python code to automatically be checked for PEP 8 compliance by Jenkins. This pull request aims to do that.

Notes:
* We may need to install [`pep8`](https://pypi.python.org/pypi/pep8) on the build server.
* I'm expecting tests to fail now that PEP 8 compliance is being checked as part of the build. I'm fine with cleaning up any remaining PEP 8 violations as part of this pull request.
* I did not understand why the RAT and scalastyle reports are saved to text files. I did the same for the PEP 8 check, but only so that the console output style can match those for the RAT and scalastyle checks. The PEP 8 report is removed right after the check is complete.
* Updates to the ["Contributing to Spark"](https://cwiki.apache.org/confluence/display/SPARK/Contributing+to+Spark) guide will be submitted elsewhere, as I don't believe that text is part of the Spark repo.

Author: Nicholas Chammas <nicholas.chammas@gmail.com>
Author: nchammas <nicholas.chammas@gmail.com>

Closes #1744 from nchammas/master and squashes the following commits:

274b238 [Nicholas Chammas] [SPARK-2627] [PySpark] minor indentation changes
983d963 [nchammas] Merge pull request #5 from apache/master
1db5314 [nchammas] Merge pull request #4 from apache/master
0e0245f [Nicholas Chammas] [SPARK-2627] undo erroneous whitespace fixes
bf30942 [Nicholas Chammas] [SPARK-2627] PEP8: comment spacing
6db9a44 [nchammas] Merge pull request #3 from apache/master
7b4750e [Nicholas Chammas] merge upstream changes
91b7584 [Nicholas Chammas] [SPARK-2627] undo unnecessary line breaks
44e3e56 [Nicholas Chammas] [SPARK-2627] use tox.ini to exclude files
b09fae2 [Nicholas Chammas] don't wrap comments unnecessarily
bfb9f9f [Nicholas Chammas] [SPARK-2627] keep up with the PEP 8 fixes
9da347f [nchammas] Merge pull request #2 from apache/master
aa5b4b5 [Nicholas Chammas] [SPARK-2627] follow Spark bash style for if blocks
d0a83b9 [Nicholas Chammas] [SPARK-2627] check that pep8 downloaded fine
dffb5dd [Nicholas Chammas] [SPARK-2627] download pep8 at runtime
a1ce7ae [Nicholas Chammas] [SPARK-2627] space out test report sections
21da538 [Nicholas Chammas] [SPARK-2627] it's PEP 8, not PEP8
6f4900b [Nicholas Chammas] [SPARK-2627] more misc PEP 8 fixes
fe57ed0 [Nicholas Chammas] removing merge conflict backups
9c01d4c [nchammas] Merge pull request #1 from apache/master
9a66cb0 [Nicholas Chammas] resolving merge conflicts
a31ccc4 [Nicholas Chammas] [SPARK-2627] miscellaneous PEP 8 fixes
beaa9ac [Nicholas Chammas] [SPARK-2627] fail check on non-zero status
723ed39 [Nicholas Chammas] always delete the report file
0541ebb [Nicholas Chammas] [SPARK-2627] call Python linter from run-tests
12440fa [Nicholas Chammas] [SPARK-2627] add Scala linter
61c07b9 [Nicholas Chammas] [SPARK-2627] add Python linter
75ad552 [Nicholas Chammas] make check output style consistent

1 files changed, 8 insertions, 6 deletions

diff --git a/python/pyspark/mllib/random.py b/python/pyspark/mllib/random.py
index 36e710dbae..eb496688b6 100644
--- a/python/pyspark/mllib/random.py
+++ b/python/pyspark/mllib/random.py
@@ -24,7 +24,9 @@ from pyspark.rdd import RDD
 from pyspark.mllib._common import _deserialize_double, _deserialize_double_vector
 from pyspark.serializers import NoOpSerializer
 
+
 class RandomRDDGenerators:
+
     """
     Generator methods for creating RDDs comprised of i.i.d samples from
     some distribution.
@@ -53,7 +55,7 @@ class RandomRDDGenerators:
         True
         """
         jrdd = sc._jvm.PythonMLLibAPI().uniformRDD(sc._jsc, size, numPartitions, seed)
-        uniform =  RDD(jrdd, sc, NoOpSerializer())
+        uniform = RDD(jrdd, sc, NoOpSerializer())
         return uniform.map(lambda bytes: _deserialize_double(bytearray(bytes)))
 
     @staticmethod
@@ -77,7 +79,7 @@ class RandomRDDGenerators:
         True
         """
         jrdd = sc._jvm.PythonMLLibAPI().normalRDD(sc._jsc, size, numPartitions, seed)
-        normal =  RDD(jrdd, sc, NoOpSerializer())
+        normal = RDD(jrdd, sc, NoOpSerializer())
         return normal.map(lambda bytes: _deserialize_double(bytearray(bytes)))
 
     @staticmethod
@@ -98,7 +100,7 @@ class RandomRDDGenerators:
         True
         """
         jrdd = sc._jvm.PythonMLLibAPI().poissonRDD(sc._jsc, mean, size, numPartitions, seed)
-        poisson =  RDD(jrdd, sc, NoOpSerializer())
+        poisson = RDD(jrdd, sc, NoOpSerializer())
         return poisson.map(lambda bytes: _deserialize_double(bytearray(bytes)))
 
     @staticmethod
@@ -118,7 +120,7 @@ class RandomRDDGenerators:
         """
         jrdd = sc._jvm.PythonMLLibAPI() \
             .uniformVectorRDD(sc._jsc, numRows, numCols, numPartitions, seed)
-        uniform =  RDD(jrdd, sc, NoOpSerializer())
+        uniform = RDD(jrdd, sc, NoOpSerializer())
         return uniform.map(lambda bytes: _deserialize_double_vector(bytearray(bytes)))
 
     @staticmethod
@@ -138,7 +140,7 @@ class RandomRDDGenerators:
         """
         jrdd = sc._jvm.PythonMLLibAPI() \
             .normalVectorRDD(sc._jsc, numRows, numCols, numPartitions, seed)
-        normal =  RDD(jrdd, sc, NoOpSerializer())
+        normal = RDD(jrdd, sc, NoOpSerializer())
         return normal.map(lambda bytes: _deserialize_double_vector(bytearray(bytes)))
 
     @staticmethod
@@ -161,7 +163,7 @@ class RandomRDDGenerators:
         """
         jrdd = sc._jvm.PythonMLLibAPI() \
             .poissonVectorRDD(sc._jsc, mean, numRows, numCols, numPartitions, seed)
-        poisson =  RDD(jrdd, sc, NoOpSerializer())
+        poisson = RDD(jrdd, sc, NoOpSerializer())
         return poisson.map(lambda bytes: _deserialize_double_vector(bytearray(bytes)))