[Ownership] Fix unit tests

Amend unit tests to resolve issues related to
changes in support of nasa/mct#123.
Specifically:

* Change method annotations in RoleAccessTest
  to clean up on a per-method basis, avoiding
  interference with global state (platform)
  in other tests.
* Perform additional mock setup in test for
  info view, as platform is now indirectly
  consulted during the creation of that GUI.