FIX: `coffee-mode` uses `coffee-tab-width` instead of `tab-width`.

And recently it has removed `tab-width` dependency completely.
Merge pull request #493 from pokehanai/hotfix/coffee-tabwidth

FIX: `coffee-mode` uses `coffee-tab-width` instead of `tab-width`.
Merge remote-tracking branch 'upstream/master'

* upstream/master:
  FIX: `coffee-mode` uses `coffee-tab-width` instead of `tab-width`.
update!