Several of the unit tests for the new key authorization feature require
read access to the GATK master private key file. Since this file is only
readable by members of the group gsagit, this makes it hard for people
outside the group to run the test suite.
Now, we skip tests that require the master private key if the private
key exists (since not existing would be a true error) but is not readable
by the user running the test suite
Bamboo, of course, will always be able to run these tests.