Depends on `chruby-fish`: https://github.com/JeanMertz/chruby-fish

set `CHRUBY_AUTO_ENABLED` to `false` to disable auto loading Ruby versions on
directory change.

set `CHRUBY_ROOT` to point to the root path of chruby. The path will be
appended by `share/chruby/chruby.fish` and `share/chruby/auto.fish`.

Add support for upcoming fish shell native vi mode

Minor updates for bobthefish

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