Updated sklearn requirement number to .18. This build breaks with sklearn <= .17.

Author: ajaysaini725

python/README.md

@@ -20,7 +20,7 @@ This package is released under the Apache 2.0 license. See the LICENSE file.
 ## Installation
 
 This package has the following requirements:
- - a recent version of scikit-learn. Version 0.17 has been tested, older versions may work too.
+ - Sklearn version >= .18.
  - Spark >= 2.0. Spark may be downloaded from the
  [Spark official website](http://spark.apache.org/). In order to use spark-sklearn, you need to use the pyspark interpreter or another Spark-compliant python interpreter. See the [Spark guide](https://spark.apache.org/docs/latest/programming-guide.html#overview) for more details.
  - [nose](https://nose.readthedocs.org) (testing dependency only)

python/requirements.txt

@@ -1,2 +1,2 @@
 # This file should list any python package dependencies.
-scikit-learn==0.17.1
+scikit-learn==0.18.1

python/setup.py

@@ -19,7 +19,7 @@
     "Programming Language :: Python",
     "Topic :: Scientific/Engineering",
 ]
-INSTALL_REQUIRES = ["scikit-learn >= 0.17"]
+INSTALL_REQUIRES = ["scikit-learn >= 0.18"]
 
 # Project root
 ROOT = os.path.abspath(os.getcwd() + "/")