Update README.textile

Added instructions for installing zsh (due to the problems with first time zsh users)
Update README.textile
Update rvm.plugin.zsh

Ruby 2.1.1 -> Ruby 2.1.2.
Merge pull request #2994 from admpsktt/patch-1

Update rvm.plugin.zsh
Merge pull request #2993 from mittalabhas1/master

Update README.textile
gitstatus compatibility with python 3
merged
fixed compatibility issue with python 2.5 and 2.6
Merge branch 'master' of github.com:Onizuka89/oh-my-zsh

Conflicts:
	plugins/git-prompt/gitstatus.py