TestRunner.run() now does the test module loading

The API of the `TestRunner.run()` has changed; instead of passing the
actual modules to run, you should now pass a list of module names to be
loaded (using RequireJS). The TestRunner now makes sure to execute the
test suites in order. Note that you still have to make sure to return a
function from the test module instead of the direct call to
`describe()`.