Fix problems with selection when all problems are filtered out

The GUI must detect this state and update the problem view.

Before this commit the list became empty but the problem view contained
data of the lastly selected problem.

Signed-off-by: Jakub Filak <jfilak@redhat.com>
Disable pylint rule for too many lines in module

Signed-off-by: Jakub Filak <jfilak@redhat.com>
New version 1.0.0