Improve ctags and company configuration

Set ctags command based on major mode
Set different company backends based on major mode
Completely abandon robe in favour of ctags for Ruby
Set up Erlang configuration

20elisp.el

@@ -1,6 +1,11 @@
 (defun activate-emacs-lisp-mode ()
   "Goodies for editing emacs files."
   (set-indent 2) ;; Default indentation of 2 characters
+  (column-enforce-n 80)
+
+  ;; Company list override
+  (add-to-list (make-local-variable 'company-backends)
+               '(company-elisp company-yasnippet))
   )
 
 (add-hook 'emacs-lisp-mode-hook 'activate-emacs-lisp-mode)