change path to search for within virtualenv on Windows

[ergodicbreak]

First pull request ever, sorry if I'm not doing something right!

See virtualenv docs at https://virtualenv.pypa.io/en/latest/userguide.html#windows-notes for reference.

[dosmoc]

Looking at testing this. Say I have a file in the root directory of a virtualenv called test_path.py that just consists of:

import sys

print sys.executable

If I add a connection to Python with the virtualenv as the root folder and evaluate these statements, the LightTable console will have the full path of Python in the Scripts folder of that virtualenv. Something like "C:\path\to\virtualenv\Scripts\python.exe". Without the changes, LightTable won't find it and something like "C:\Python27\python.exe" will be printed. That sound about right?

[ergodicbreak]

@dosmoc yes, that sounds right. I haven't looked at this in a while -- been meaning to test the new Atom build for Windows.