Update main for new interface to media_clock_server.

   This commit relates to the change in sc_avb to have an
   interface connection to control the media clock server.
Merge pull request #19 from davelxmos/opt_interfaces

Update main for new interface to media_clock_server.
Start adding support to the test infrastructure for the open-source controller.
Fix issue with false matches because elements are able to be matched twice.
Put the expected in a sequence to invalid failures.
Merge git://github.com/xcore/sw_avb_dc