Add autocompletion for Rails3.

+ Originally published by Christopher Chow.
+ Source:
https://github.com/robbyrussell/oh-my-zsh/blob/30620d463850c17f86e7a56fbf6a8b5e793a4e07/plugins/rails3/_rails3
  Commit: 30620d463850c17f86e7a56fbf6a8b5e793a4e07
Change duplicated alias name
rvm plugin: update to ruby version helpers and rvm-update

* the current patch levels hard-coded here are pretty dated. I updated the ruby version helpers to use loose ruby version matchers so they don't continually need to be updated with every new patch level release.

* `rvm get head` actually performs an `rvm reload` in the post install. there's no need to do again here in rvm-update so I've removed that.
The current version of bower is completely unavailable, plugin depth modification
Update coffee completion
Merge pull request #1917 from brandonblack/rvm-plugin

rvm plugin: update to ruby version helpers and rvm-update
Merge pull request #1919 from dongweiming/breaking-change-bower

The current version of bower is completely unavailable, plugin depthmodification
Merge pull request #1916 from okuramasafumi/master

Change duplicated alias name
Merge pull request #1920 from dongweiming/update-coffee

Update coffee completion
Merge pull request #1764 from johnjohndoe/feature/rails3-autocompletion

Add autocompletion for Rails3.
Merge remote-tracking branch 'robby/master'