PHPUnit tests under Drupal

Sadly, we still require that the environment is already configured with MySQL,
that schemas have been installed, and modules enabled.

This patch makes it simple to write new PHPUnit tests.  If your test is self-
contained, extend the PHPUnit_Framework_TestCase class as usual.  If you need
to bootstrap Drupal, access a databases, or call into other modules, please
have your test extend BaseWmfDrupalPhpUnitTestCase.

TODO:
* There is no transaction on the database.  We need to allow two modes, the
default being to rollback changes made during each test.  In debugging mode,
changes will persist so you may examine them manually.

Change-Id: Ibc90555de8fc910c5435d2b0ca83691f51498939
Merge "PHPUnit tests under Drupal"