Clean up test database after tests

Fixes #1064

- Updated grunt config for unit and functional tests to remove the test
database after each is run.
- Cleaned up a couple of issues with the functional tests that may have
been causing travis builds to fail randomly, including: the start page
is now `about:blank` instead of whatever page the last test suite left
off at, added some checks in the logout tests to ensure they're truly
independent of the other test suites.
Merge pull request #1067 from gotdibbs/Issue1064

Clean up test database after tests