[packagekit] APT backend replaced

[Sebastian Heinlein]

Hello,

with commit 922a9bcc039b3e34e6577f6324609b56f2e2422f I replaced the
helper based apt backend by the DBus based one. I did so, since the new
backend provides the same and more features and the former one has not
been adapted to the api changes for the last couple of monthes.

The old apt backend was renamed to apt.deprecated.

Cheers,

Sebastian