test: create, create errors

[abesto]

There are a ton of tests in test_objects.rb in Stunt; might as well land them in smaller chunks. Points of interest:

• Broke the objects tests up into individual files, one per test method in test_objects.rb. Should make working with them a bit simpler.
• Added msg to a warn! in task.rs to print the kind of exception the task hit. This has nothing to do with the tests, other than: it made things mildly easier to understand / debug.
• Added missing create() permission checks