Added decorator for extension tests
Added decorator for extension tests

The added decorator (in high-level tests) will
skip the test if the extension is not present
on the system being tested, leaving an appropriate
message behind

frozencemetery/python-gssapi,pythongssapi/python-gssapi,pythongssapi/python-gssapi,pythongssapi/python-gssapi,frozencemetery/python-gssapi,frozencemetery/python-gssapi