The testing infrastructure was fine for the Review Board API tests, but

wasn't as nice to work with for anything else that wanted to reuse the

test infrastructure. In particular, the assumption was made that all

APIs can be bound to a Local Site, but this isn't always true.
This assumption has been removed. The default is still to test APIs

against a Local Site, but by setting test_local_sites = False, this

will be turned off.
Along with this, create_repository() can now accept a local_site=

parameter, and subclasses of BaseWebAPITestCase can now override the

mimetype for expected errors.

RB unit tests pass.
Used this in another set of tests, and they worked as well.