Don't set node-info if version is 'none'

This is done to make it easier to not show node-info in themes
when no node version is currently in use. This is consistent with
how the Python module's python-info works.
tbekolay zprezto customizations.

- Includes tbekolay theme! Which is the best.
Changed path for npm
virtualenv fixes
Some Python changes for OS X
zshenv changes
Some mac os x specific things
Debian virtualenvwrapper update
Moved things around based on recent updates
Added gpg to modules
Added node / nvm to shell