trivial: Allow GsAppState to back to UNKNOWN from any state

We'll need this if we want to be clever and work around the state machine.
Do not use the application state to modify how widgets are drawn

It's not nice to change the way the widget works using a special state value.
Instead of this, provide a method that only the updates panel will use and make
things less magic.
When de-duplicating packages preserve the updatable state
When de-duplicating packages get useful data from the old package
trivial: Remove some over-verbose startup debugging
If PackageKit returns installed available packages then mark the app as updatable
Show a overlay of 'Updates' for updatable applications
trivial: Actually merge the translations in the AppData file