Add Enhanced Ruby Mode

And make it the new default for editing Ruby source code.
Add rbenv integration
Fix insertion of "end" when editing ruby
Add rspec integration
Remove YARi
Fix path initialization

exec-path-from-shell-initialize gets autoloaded.
Remove emacs-starter-kit language helpers

First step towards the next iteration of my config: Rebuilt from the
ground up for 24.4.
Remove startup message from scratch buffer
Initial multi-term-setup