Sync .virtualenvs from VM to home/.virtualenvs [#25]

Update notice: existing virtualenvs will not work, need to recreate virtualenvs
$ vagrant reload to get the changes
Sync .virtualenvs from VM to home/.virtualenvs: windows symlink [#25]

To make virtualenv work, you must run git bash and virtualbox as administrator on windows.

How to update:
+ $ git fetch origin
+ $ git merge origin/master
+ restart windows
+ from now on, *always* run virtualbox and git bash as *administrator*

And it's all, you can use vagrant as normal.
Sync .virtualenvs from VM to home/.virtualenvs: update README [#25]