Fix slow tests to not actually sleep

These two tests were causing the unit tests to
take 2min40secs to run.  The fix is to patch time.sleep
because we don't actually actually need to sleep during
the tests.

I also updated the tests to be more idiomatic including:

* Don't need to define setUp() if you're just calling super()
* Prefer assertRaises(), this gives better failure messages
  and is easier to read.
Merge branch 'fix-slow-tests' into develop

* fix-slow-tests:
  Fix slow tests to not actually sleep