Moved the test 'skip_all' from GenomeDiskAllocationTest.pm to the individual tests

Another test (SoftwareResult_ambiguous_property_definitions.t) was failing
because it does a 'ur show subclasses', which internally loads everything
that looks like a .pm file.

As GenomeDiskAllocationTest.pm loaded, the 'skip_all' told the test harness
that SoftwareResult_ambiguous_property_definitions.t should skip.
Merge branch 'master' of ssh://git/srv/git/genome