koops parse: support <NMI> frame prefix

Closes #648

Signed-off-by: Jakub Filak <jfilak@redhat.com>
Signed-off-by: Richard Marko <rmarko@redhat.com>
unittest: add test for <NMI> koops frame prefix

Related to #648

Signed-off-by: Jakub Filak <jfilak@redhat.com>
Signed-off-by: Richard Marko <rmarko@redhat.com>
abrt-python: pep8 cleanup

Signed-off-by: Richard Marko <rmarko@redhat.com>
abrt-python: fix bug in problem.get

Signed-off-by: Richard Marko <rmarko@redhat.com>