trivial: Fix make check
Use a standard GAsyncReadyCallback when installing and removing packages

Additionally, this gives us both sync and async versions of all the action
methods, which we'll need for future functionality.
Run the local ratings plugin before the hardcoded one

If the user has already set a rating, use that rather than the canned value.
Save the user rating if the user clicks the rating stars

A the moment this is just saved locally, but could be sent to a web service in
future versions.