Create unit tests that mock all circumstances where submissions fail

[robyngit]

We have documented a number of cases where a data package fails to upload for some reason and MetacatUI does not handle those issues gracefully. As a first step to fixing these issues, we need to create unit tests that imitate these circumstances so that later we can verify that MetacatUI handles them gracefully. The issues in the MetacatUI submission & error handling project could be reviewed to help come up with the list of cases to mock.