ASGARD-1176 - Shorter system error email subject lines

More relevant too, using the root cause.
Make raw instance log output null safe
Fix bug in /instance/appversions
Show VPC on security group list, because when we hit a limit in a VPC it helps to be able to filter the list on that VPC ID
ASGARD-629 - Security group should display dependencies

This way it's a lot easier to find most of the things that need to get deleted before you're allowed to delete the security group.
Stop logging garbage about missing image tags
Fix offline mode to stop constantly trying to create workflow domain
Speed up slowest unit tests
Fix unit test to match current method signature (soon to be changed)
Fix security controller unit tests
Make unit test future proof for changing number of method arguments
Merge pull request #362 from joesondow/ASGARD-629-Security-group-dependencies

ASGARD-629 - Security group should display dependencies
Merge pull request #361 from joesondow/Improve-logs-and-tests

Misc - reduce noisy log messages and speed up some unit tests
Merge pull request #360 from joesondow/ASGARD-1176-system-error-email-subjects

ASGARD-1176 Shorter, more relevant system error email subject lines