[BUILD] - Data-source unit-tests should share the same JVM, this makes
things faster once the caches of the underlying data-base are filled.
[BUILD] - Speed up test runs; ModelPrinter can return early if there
is nothing to print; DebugRunner can produce pages in batches for quicker
results.
Merge pull request #363 from tmorgner/build-longrun

Build and test refactorings so that tests run a bit faster.