org: refactor + fix incorrectly attached hooks
org: refactor + fix incorrectly attached hooks

Buffer-local hooks were being added on org-load-hook, rather than
org-mode-hook.

Fixes #186

hlissner/doom-emacs,UndeadKernel/emacs_doom,UndeadKernel/emacs_doom,hlissner/doom-emacs,hlissner/.emacs.d,hlissner/.emacs.d,aminb/.emacs.d,UndeadKernel/emacs_doom,UndeadKernel/emacs_doom,UndeadKernel/emacs_doom,aminb/.emacs.d,hlissner/.emacs.d,aminb/.emacs.d,hlissner/doom-emacs,aminb/.emacs.d,hlissner/.emacs.d,aminb/.emacs.d,UndeadKernel/emacs_doom,hlissner/.emacs.d,aminb/.emacs.d,UndeadKernel/emacs_doom,hlissner/.emacs.d,hlissner/.emacs.d,hlissner/.emacs.d,hlissner/doom-emacs,hlissner/doom-emacs,aminb/.emacs.d,aminb/.emacs.d,hlissner/doom-emacs,hlissner/doom-emacs