Fix spurious test failure in Combobox unit test.
Fix spurious test failure in Combobox unit test.

The timing in the previous version was too brittle.  It created the Comboboxes
in the beforeEach() preamble, and then called on("query-success", ...) in the main test
block, assuming that the "query-success" event had not yet fired.  But (perhaps due to
the Intern 3 upgrade) the event was firing before the main test block started.

Also, the main test block was strangley called "Store.add/remove/put" even though
it wasn't doing any of those things.

Also did some general cleanup.

brunano21/deliteful,brunano21/deliteful