all: Remove theme install code

https://bugzilla.gnome.org/show_bug.cgi?id=672604
debug: Remove property editor

Just use the gtk+ inspector.
appdata: Add appdata skeleton

https://bugzilla.gnome.org/show_bug.cgi?id=729724
packagekit: Remove catalogue

Package catalogue support has apparently been removed from packagekit 3.12.

https://bugzilla.gnome.org/show_bug.cgi?id=672604