Remove vendored version of package.el

package.el is included in Emacs 24 and having this older version
around was causing problems. Specifically this error was generated
when trying to install the flycheck package:

    Package `emacs-24.1' is unavailable

Removing the vendored copy of package.el fixes this.
inf-ruby-keys is no more

This has been renamed to inf-ruby-setup-keybindings and is called
automatically when setting up inf-ruby.