multiple current tests and meaningful module name

Hi,

We ran across this issue when we tried to use qunit-reporter-junit with phantomjs and asynchronous tests.
It seems there is a legal case where the testStart callback is called for several tests in a row although although the prior one hasn't ended yet so I basically extended the currentTest variable to be a dictionary of current tests. This solved the problem for us.
I also implemented a method that tries to provide a meaningful modul name in case the test doesn't provide one, which makes it better for some cases and at least not worse for others.

regards

Reinhold

The second argument is redundant (only extra overhead of scope chain and property access lookups).