Updated README.md to fix #230

Thanks @p5k6!
Add chruby and chruby-auto plugins

  * chruby.bash loads chruby
  * chruby-auto.bash loads chruby and enables auto-switching
  * add chruby_version_prompt() function for displaying ruby version
  * inspired by https://gist.github.com/rssvihla/6153455
Added custom bash prompt, based on the 'my' theme.

This colors the arrow at the start of the second line based on the exit
code of the last command: green for 0, red for non-zero

This functionality currently fails when the 'fasd' plugin is enabled,
since it is messing with the PROMPT_COMMAND function.
Merge pull request #235 from nwinkler/nwinkler_theme

Added custom bash prompt
Merge pull request #233 from aramprice/master

Add chruby and chruby-auto plugins
Added support to show commits ahead, commits behind and stashes count in Git
through variables
Added Powerline theme
Added Powerline-plain theme
Added first version of git-svn aliases
Merge pull request #239 from nwinkler/git-svn-aliases

git-svn aliases
Fixed wrong number for white color in Powerline and Powerline-plain themes
Now, really fixed wrong number for white color in Powerline and Powerline-plain themes
Merge pull request #229 from oddjobsman/master

Added Sexy Bash Prompt suggested by @addyosmani in "A Toolbelt For The M...
Merge remote-tracking branch 'edubxb/master'
Trim the whitespace from git stash output
Update to show the difference between staged, unstaged, and untracked files
Add a fallback in case Git isn't being used (*shutters*)
Added aliases for Vagrant
Added new aliases and plugins for git
Removed due to Git handling this automatically

See this discussion https://github.com/revans/bash-it/pull/242/files#r7964126