Use IntegationTestCase.

With ControllerTestCase going away, it is a good idea to go to
IntegrationTestCase sooner than later.
Add templates I forgot about the first time around.
Remove .json extension

Having it makes postgres really grumpy as the value no longer looks like
a uuid.
Merge pull request #244 from cakephp/use-integration-test

Use IntegationTestCase for controller tests.