Add coffee-mode package from MELPA
Add literate-coffee-mode package from MELPA
Trigger my prog-mode-hook for coffee-mode files

I should really register that for prog-modes and only call it explicitly
for modes that don't extend prog-mode.
Add coffee and coffeelint commands for flycheck
Use my-prog-mode-init as a prog-mode-hook

and remove it from mode hooks for modes that extend prog-mode.

Hurrah