storage: move lob deletion event, add test

Separate events.py file introduced for adding
further events to ease denormalization
required for backtrace quality computation.

Signed-off-by: Richard Marko <rmarko@redhat.com>
storage: add denormalized backtrace quality field

On-demand computation is too demanding
making queries for hot/longterm problems
taking way too long.

This patch introduces ReportBacktrace.quality
field which is updated on ReportBacktrace
creation and updates.

Signed-off-by: Richard Marko <rmarko@redhat.com>
fixup! storage: add denormalized backtrace quality field
fixup! storage: move lob deletion event, add test
tests: delete lob dir between tests

Signed-off-by: Richard Marko <rmarko@fedoraproject.org>
storage: lower quality if frame is not reliable

Signed-off-by: Richard Marko <rmarko@fedoraproject.org>
Merge pull request #232 from abrt/bt_quality

Store backtrace quality information in database