More flexibility in allowed test output.

Groovy 2.3 will produce a warning if run on < 1.7 since
it will try to load some classes that have been compiled
with 1.7. This breaks tests that are strict on expected
behaviour. I changed the harness to allow for this
warning message in some circumstances and still continue
with the test.
Adjusted to not rely on CompilerOptions constant that isn't in < 1.8 compiler
Adjusted to not rely on CompilerOptions constant that isn't in < 1.8 compiler
GRECLIPSE-1725. Eclipse hangs issue on Greclipse code assist scenario
Merge pull request #28 from BoykoAlex/GRECLIPSE-1725

GRECLIPSE-1725. Eclipse hangs issue on Greclipse code assist scenario
reducing test fragility