Added vim-ruby plugin
Added vim-haml plugin
Added vim-coffee-script plugin
Added vim-slim plugin
Separated filetype specific config from .vimrc
Added ruby specific indentation settings in vim
Added ruby specific configuration files

* Added rbenv plugins
* Added gemrc
Refactored zshrc

Split all the settings into different files (in the zsh directory). This
way, the structure is more modular and easier to manage.