Add a vundle plugin similiar to that found in oh-my-zsh

In robbyrussell, when last status is 0, the prompt should be green, otherwise it should be red, just like oh-my-zsh

Allowing arguments to be passed to _python

I'm brand new to fish so I'm not sure if this is a fix of if I'm doing something incorrectly.  On fish version 2.1.0 on osx 10.9.2 running pyhttp doesn't start the http server, instead only starts the python shell.  This fixes that issue for me at least.

Previously, 'set $path...' ran regardless of the result of 'and not contains...'. This fixes _append_path to actually use the result of the condition check.

fix z path scope