FEATURE: parallel test support

[stevebuik]

currently the samples use a single chain of promises. This could, in many cases, be run in parallel and drive N components concurrently in a test page. The tricky part will be recombining all the failures and passes at the end of each fork into an overall success.

There is support for "all" in some promise implementations so this could be used to recombine all the fork results.

The benefit will be faster test runs when testing N components at the same time.