Introduce helpers for management of list of ignored problems

The current implementation stores a set of ignored problems in a csv
file

Each ignored problem corresponds to a single line in the file.
Each line has the following format 'PROBLEM ID;UUID;DUPHASH'.
The matching function returns logical true if any line value equals to
the corresponding problem value

Related to rhbz#909968 and rhbz#905412

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
applet: mark problems as ignored and don't notify ignored problems

- the ignore button just closed a notify bubble until this patch
- from now the ignore button marks a problem as ignored in the future

- closes rhbz#909968 and rhbz#905412

Signed-off-by: Jakub Filak <jfilak@redhat.com>
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>