support both PackageKit 0.7.x and 0.8.x
Fix redirection after sign in
- devise expects a path returned from method after_sign_in_from()
- templates for create action are not needed, even they are the reason
  for rendering empty page with layout only
Add missing hash sign to fix erb comment
Adjust repository to new package kit api
Add missing dependency on yast2-users
Adapt to changed PackageKit api:
- add textual description to packagekit dbus code
- humanize the description in view