Improve data caching

Average time required for loading 60 Kerneloopses()
Before: 6.8s
After : 2.2s

But this patch still doesn't make start up faster for the worst case
when all of the problems are different and none of them has a desktop
entry.

Related to rhbz#963054

Signed-off-by: Jakub Filak <jfilak@redhat.com>
Signed-off-by: Richard Marko <rmarko@fedoraproject.org>
Download more problem elements in a single D-Bus call

Average time required for loading 60 Kerneloopses()
Before : 2.2s
After  : 1.4s

This commit has performance impact in all cases.

Related to rhbz#963054

Signed-off-by: Jakub Filak <jfilak@redhat.com>
Signed-off-by: Richard Marko <rmarko@fedoraproject.org>
Remember missing elements and load them only once

Average time required for loading 60 Kerneloopses()
Before : 1.4s
After  : 1.1s

This commit has performance impact in all cases.

Related to rhbz#963054

Signed-off-by: Jakub Filak <jfilak@redhat.com>
Signed-off-by: Richard Marko <rmarko@fedoraproject.org>