Added replication VM power control test

This tests VM power control from the replication parent of a child appliance.
I'm curious with regard to this test class. I'm not sure it needs to exist, unless there's some sleight-of-hand going on to make the `random_provider` usefixtures mark work along with the module-scope pytes_generate_tests above. If that's the case, this test should probably be in its own module, with its own generate_tests hook to deliver the random provider (which [testgen](https://github.com/RedHatQE/cfme_tests/blob/master/utils/testgen.py#L171) knows how to do)