Generate static site tests.

This will publish a ember-tests.html static test site along with the
builds. This makes it extremely simple to test the latest
canary/beta/release builds on various devices. It is also critical to
the cross-browser testing that we have been working on.

This depends on changes in #3591.
Merge pull request #3592 from rjackson/static_test_generator

Generate static site tests.