Tap testing

The basic goal of this pull request is to implement 'make check' for dbus-test.html.

Along the way:
 * Switched to TAP output for tests
 * Integrated that into automake
 * Made test-server run without privileges
 * Fixed several bugs in test-server and friends
 * Updated qunit
 * Included qunit-tap
 * Implemented a phantom driver for TAP output for qunit + qunit-tap