Install virtualenv on OSX

Choose whether you want OSX python or home brew version. When you choose home brew run:

brew install python

Then install virtualenv:

pip install virtualenv
pip install virtualenvwrapper
mkdir -p .virtualenvs

Add some conf stuff to your .bash_profile or .bash_rc

### Virtual envs
export WORKON_HOME=$HOME/.virtualenvs
export PROJECT_HOME=$HOME/GIT
source /usr/local/bin/virtualenvwrapper.sh