QUnit addons cannot be used

Plugins such as qunit-reporter-junit (https://github.com/jquery/qunit-reporter-junit) or qunit-tap (https://github.com/twada/qunit-tap) require access to the QUnit global object to add their functionality, which is not exposed when using node-qunit. It would be very useful to be able to use these resources, since they expand the functionality of qunit so it can be used in a CI platform.
