Update interface.rng and xml test files to match netcf 0.1.5

Update interface.rng and xml test files to match netcf 0.1.5

The RNG now supports IPv6 and bonds attached to bridges, along with
some other minor tweaks. All test files from netcf have been copied to
the test directory and added to the xml2xml and schema tests (and they
all pass, of course ;-)