Couple of fixes

In relation to https://github.com/milkypostman/melpa/pull/1395:

* Format header line so it can be parsed by package.el (*)
* Explicitly require 'skewer-mode
* Remove comment about hook modification being bad style: it's fine in this case

Cheers,

-Steve

(* If you enable `auto-insert-mode`, Emacs will prompt you to insert the standard boilerplate when you create a new .el file)