Add in Python Virtualy Environment Activation

Needs to have some wrapper code to create the virtualenv if
it doesn't exist.  I will worry about that later when I actually
update the other systems I have this repo checked out on.
Fix issue with TMUX on Ubuntu

On Ubuntu, TMUX sets $TERM to "screen" which doesn't help my logic
in the file. So inorder to get around garbage at the bottom of my
screen, we also check that $TMUX doesn't exist and we are good.