Allow INSTALLING->AVAILABLE and REMOVING->INSTALLED if the action fails beore completing
Add functionality so that history objects can be added to GsApp
trivial: Only print the number of related packages if there have been some set
trivial: Fix alignment when dumping GsApp objects to a string
Add a packagekit-history plugin that sets history data on applications

This only adds 66ms to the GUI startup, and allows us to implement the
list ordering-by-date, the post-offline-updates UI and the installed details view.

You need PackageKit from git master before this will populate details.