add virtualenvwrapper support

Hi,

I use virtualenvwrapper, and it is not supported.
Do you know if it is possible to add this functionality?
You can use the $VIRTUAL_ENV to know where the ENV is installed
For exemple:
`> echo $VIRTUAL_ENV `
`/home/USER/.virtualenv/ENV`

Thanks,
Mic

The issue names no files, tests, or entry points. Start by locating how ide-python discovers and selects virtual environments, then check how the VIRTUAL_ENV value from virtualenvwrapper could be recognized; done means a virtualenvwrapper environment is detected and usable by the Atom Python support.

Written by the indexing model from the issue text.