DRY up code by using `Cache::w` for `Workflows` object

No need to create a whole separate `Workflows` object inside the `Repo` object, as we already have one instantiated inside `Repo::cache` (aka, `$this->cache`, in the scope of the `Repo` class).

This is a somewhat ambitious refactor, but the modifications were tested in all of the repo searches.

While testing this, I discovered two things:

1. The Grunt search is still broken
	* This is already covered by #30
2. The PEAR search is a bit dodgy; it brings in the “register” link as the first search results.
	* A new issue has been filed for this (#45)