Test in quick mode for ant build

Add a target `test.suite.quick`.

Let test.quick depend only on init and quick.done,
and load the task using the quick path (with non-core deps).

As mentioned on the ML.  This would be more useful if
partest task had a failed attribute to ask ant runner to run
failed tests.  We'll have to ask the partest guys for that.

Review by @adriaanm in case it is useful.