Disable flyspell-mode in git-commit-mode

It seems like enabling flyspell-mode within git-commit-mode causes
Emacs to completely freeze up, requring a force quit.

modules/siren-magit.el

@@ -38,7 +38,7 @@
 (defun siren-git-commit-mode-defaults ()
   (subword-mode)
   (setq tab-width 2)
-  (flyspell-mode)
+  ;; (flyspell-mode) ;; in GUI causes git-commit-mode to lock up emacs
   (linum-mode t)
   (auto-fill-mode))