osx-setup.sh post-install commands

Added pip and npm packages (virtualenvwrapper, jade)
Added comments
Updated iTerm preferences
Added grip helper command to vimrc

Use Grip to compile and watch with `grip`, background the process, and
then open the default web browser to
[localhost](http://localhost:5000/).

NOTE: this command does not work. Backgrounding grip for whatever reason
doesn't work using the `&` at the end of the command.
Added gcm git command
Added shortcut to reset macbook hostname