Make it hard to do the wrong thing in tests

Matt had to fix some tests this week in which he was encountering errors because the tests were trying to connect to the real charm store, rather than using our fake charm store.  We want to make it hard to do this.

Rick pointed out that if we change our app configuration for tests in the initialization (say, for instance, in the test’s index.html) to an empty value then we will use a fake store.  We agreed that this was a simple, good approach, and Matt created a card for it.