Samba4/Tests

Test coverage information (regularly updated) can be found here:

* http://samba.org/~jelmer/samba_coverage/
* http://samba.org/~jelmer/pidl_coverage/

Some of the things I'm working on improving:

* Use selftest.pl
* Get smbtorture to output subunit data and use that for more granular test failure results
* call lcov after each test so we can record which test covers which lines
* move 'known failures' list to selftest.pl