Disable Rubygem documentation to make Bundler fast

Ref.:
https://github.com/thoughtbot/dotfiles/commit/ddfb1300251acf8fe9fc90a8ac
af017af5e43e49
Use --no-document during gem install

Instead of older form `--no-rdoc --no-ri`
Executable python scripts are in /usr/local/share/python no more!

So says homebrew. ;-)
Merge branch 'master' of https://github.com/exalted/dotfiles

Conflicts:
	README.md