Code review comment for lp:~gmb/launchpad/blobjob-cronscript-bug-513190

This branch adds a cronscript to run ProcessApportBlob jobs. These jobs are created when a new Apport BLOB is uploaded. The idea is that the processing of large BLOBs should be done outside the request, so that +filebug will no longer time out due to the size of uploaded data.

== configs/development/launchpad-lazr.conf ==

 - I've added an error_dir directive for the process_apport_blobs
   script.

== configs/testrunner/launchpad-lazr.conf ==

 - I've added error_dir and oops_prefix directives for the
   process_apport_blobs script.

== cronscripts/process-apport-blobs.py ==

 - I've created a new cronscript based on JobCronScript to run the
   ProcessApportBlob jobs.

== database/schema/security.cfg ==

 - I've added the necessary permissions for the script's db user.

== lib/canonical/config/schema-lazr.conf ==

 - I've added basic config options for the script.

== lib/canonical/launchpad/browser/temporaryblobstorage.py ==

 - I've updated the TemporaryBlobStorageAddView to ensure that errors
   are handled properly if the librarian isn't available for some
   reason.

== lib/lp/bugs/tests/test_apportjob.py ==

 - I've added a test to ensure that the cronscript runs.

No lint.