Making virtualenv work fine with current version of things.

removed VIRTUALENV_DISTRIBUTE because it seems to be not supported anymore.
Added
export PIP_VIRTUALENV_BASE=$WORKON_HOME
export PIP_RESPECT_VIRTUALENV=true
http://virtualenvwrapper.readthedocs.org/en/latest/tips.html#tying-to-pip-s-virtualenv-support
gitgutter -> signify