Add skipIf and destructiveTest
Add skipIf and destructiveTest

These tests must be run as root, and create and destroy a user and
group, so this adds the proper decorators.

Additionally, this wraps the assertions from these tests in a try/except
block that ensures that the temp directory created for this test is
cleaned up.

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt