* ruby-mode.el: Clean up keybindings.

* ruby-mode.el: Clean up keybindings.
(ruby-mode-map): Don't bind ruby-electric-brace,
ruby-beginning-of-defun, ruby-end-of-defun, ruby-mark-defun,
backward-kill-word, reindent-then-newline-and-indent.
(ruby-mark-defun): Remove.
(ruby-electric-brace): Remove.  Obsoleted by electric-indent-chars.
(ruby-mode): Set local beginning-of-defun-function and
end-of-defun-function values.