Moves database setup/teardown closer to its usage

The setup code needed third party Python modules that are not Python 3
compatible to be imported. This made it impossible to run any test under
Python 3 without doing a bit of sys.modules magic.

bp python3

Change-Id: Ife1af897018b95c9f22c5aa42cd9319a4182b58d
Removes some duplicate setup from a testcase

TestTokenRevokeSelfAndAdmin.load_sample_data was populating the default
domain unnecessarily. It was already being populated by the parent class
RestfulTestCase.

Change-Id: I0af0947dcff00f0594227227c6c8ee7e41813f6e
Merge "Moves database setup/teardown closer to its usage"
Merge "Removes some duplicate setup from a testcase"