don't consider crashes posted to ABRT server as reported

ABRT server uses the same logic. A crash is considered as reported only
if a bugzilla bug is attached to this crash.

ABRT has to allow users to report a crash to Bugzilla because ABRT server
does not support interaction between reporters and developers.

Closes rhbz#1018570

Signed-off-by: Jakub Filak <jfilak@redhat.com>
Merge pull request #730 from abrt/rhbz1018570

Allow reporting to Bugzilla if already reported to ABRT server