install: [py 3.5] cm install on windows

[gouravshenoy]

Python 3.5 on windows mandates installation of Microsoft Visual Studio (Community Edition) for installing certain packages like "pycrypto". Installation requires ~30GB and takes ~3-4hrs. Python 2.7 required only the Microsoft C++ compiler (much lighter).

Alternatively we can download pre-compiled libraries and install.
Create a windows documentation for this and add a note that windows users use python 2.7 for the time being.