Fix setup.py to resolve numpy requirement

 If we try to install scikit with some command like:
 "pip install numpy scipy scikit-learn" or via requirements.txt which has:

 numpy 
 scipy
 scikit-learn
 
 It raises "from numpy.distutils.core import setup
 ImportError: No module named numpy.distutils.core"; because of numpy
 requirement. There was similar issue in scipy which was resolved. I adapted the patch for scikit, and was able to fix it. 

This fix is based of issue and fixes in Scipy:
https://github.com/scipy/scipy/pull/453
https://github.com/branden/scipy/commit/ad0dd3e883ca5b241dda6136eee921eb900077a0

Notes:
 -Please note that this, obviously will work with similarly patched version of scipy.
  [As far as I know the patch is on master but not on the stable release.
  Hence pip install numpy scipy scikit might not work presently unless you install 
  with requirements file which has the link to the scipy source or your own patched version
  with above fixes in place]