Upgrade QUnit.

Also switch qunit, jquery in tests to use bower.
Add explicit `expect` to each test.
Improve tests.

- fail with RSVP.onerror
- fixup some assertion messages
Split browser tests.

This way we can run just the IE tests on saucelabs.
Stop testing IE9.

We are seeing issues on SauceLabs where `stop` seems to be invalidating after a
few hundred ms despite having a 30s timeout.  When it happens, it seems to
happen exactly once: the whole suite passes except for one test with a timeout
error but timings that are off by orders of magnitude.

This seems to happen only in IE9.