[SPARK-2434][MLlib]: Warning messages that point users to original MLlib implementations added to Examples

[SPARK-2434][MLlib]: Warning messages that refer users to the original MLlib implementations of some popular example machine learning algorithms added both in the comments and the code. The following examples have been modified:
Scala:
* LocalALS
* LocalFileLR
* LocalKMeans
* LocalLP
* SparkALS
* SparkHdfsLR
* SparkKMeans
* SparkLR
Python:
 * kmeans.py
 * als.py
 * logistic_regression.py

Author: Burak <brkyvz@gmail.com>

Closes #1515 from brkyvz/SPARK-2434 and squashes the following commits:

7505da9 [Burak] [SPARK-2434][MLlib]: Warning messages added, scalastyle errors fixed, and added missing punctuation
b96b522 [Burak] [SPARK-2434][MLlib]: Warning messages added and scalastyle errors fixed
4762f39 [Burak] [SPARK-2434]: Warning messages added
17d3d83 [Burak] SPARK-2434: Added warning messages to the naive implementations of the example algorithms
2cb5301 [Burak] SPARK-2434: Warning messages redirecting to original implementaions added.

1 files changed, 6 insertions, 0 deletions

diff --git a/examples/src/main/python/logistic_regression.py b/examples/src/main/python/logistic_regression.py
index 6c33deabfd..8456b272f9 100755
--- a/examples/src/main/python/logistic_regression.py
+++ b/examples/src/main/python/logistic_regression.py
@@ -47,9 +47,15 @@ def readPointBatch(iterator):
     return [matrix]
 
 if __name__ == "__main__":
+
     if len(sys.argv) != 3:
         print >> sys.stderr, "Usage: logistic_regression <file> <iterations>"
         exit(-1)
+
+    print >> sys.stderr,  """WARN: This is a naive implementation of Logistic Regression and is
+      given as an example! Please refer to examples/src/main/python/mllib/logistic_regression.py
+      to see how MLlib's implementation is used."""
+
     sc = SparkContext(appName="PythonLR")
     points = sc.textFile(sys.argv[1]).mapPartitions(readPointBatch).cache()
     iterations = int(sys.argv[2])