Enable asserts for "ant checkTest"
Currently "ant checkTest" skips asserts. They should be enabled for all testing.
While we're at it, I wondered about:
Some answer on StackOverflow states:
"There is no performance benefit of setting java.awt.headless=true if you're not using AWT features. AWT features are loaded on-demand."
I'm adding it simply for consistency with other <junit > targets.