Handle DBus initialization errors gracefully

Recover from DBus errors and continue without DBus.

Closes rhbz#952915

Signed-off-by: Jakub Filak <jfilak@redhat.com>
Signed-off-by: Jiri Moskovcak <jmoskovc@redhat.com>
Catch InvalidProblem exception in sort function

Closes rhbz#956914

Signed-off-by: Jakub Filak <jfilak@redhat.com>
Signed-off-by: Jiri Moskovcak <jmoskovc@redhat.com>
Don't try to select a problem if the list is empty

Closes rhbz#958237

Signed-off-by: Jakub Filak <jfilak@redhat.com>
Signed-off-by: Jiri Moskovcak <jmoskovc@redhat.com>