Remove ruby-tools-mode

It's not really maintained and the most useful feature it
had (toggling between single and double quoted strings was added to
ruby-mode itself).

modules/prelude-ruby.el

@@ -34,7 +34,7 @@
 
 (require 'prelude-programming)
 
-(prelude-require-packages '(ruby-tools inf-ruby yari))
+(prelude-require-packages '(inf-ruby yari))
 
 ;; Rake files are ruby, too, as are gemspecs, rackup files, and gemfiles.
 (add-to-list 'auto-mode-alist '("\\.rake\\'" . ruby-mode))
@@ -65,7 +65,6 @@
   '(progn
      (defun prelude-ruby-mode-defaults ()
        (inf-ruby-minor-mode +1)
-       (ruby-tools-mode +1)
        ;; CamelCase aware editing operations
        (subword-mode +1))