For setting:
- name
- topic
- history visibility
- power levels
Testing RoomSettings required more stubbing on the matrix client.
The power level tests should be failing at this commit, with
fixes being made in upcoming commits.
Some tests are marked as known failures that we should fix but
aren't necessarily bugs:
- SettingStore.setValue is used when saving despite the user not
having made a change.
- Testing directory publicity changes cannot be tested because we
update state asynchronously in componentWillMount (which we do
not block on in beforeEach).
Also, we needed to use `export default` to make sure everything
uses the same client peg and client.
