trivial: Never show the 'Update' button in the UI
Copy the GsApp id when using the app cache

The GsApp originally backing that data might get removed later.
Show more detailed version numbers when required

If we make the version numbers 'pretty' we can get to a situation where we show
the same version string for the installed package *and* the update.
If this happens, make the version number progressively more un-pretty until the
version numbers differ.

Resolves: https://bugzilla.gnome.org/show_bug.cgi?id=707820