Offer a framework to provide specific VM configuration per environment

[denkab]

Currently, at least some of the Java VM-based tests run Java with default settings, which has a few substantial problems, starting with:

1. sub-optimal configuration per test: different tests may need to tune VM accordingly
2. sub-optimal configuration per hardware class: peak vs ec2 are substantially different and require tuning

More trivially, lack of visibility into VM garbage collector behavior is not productive in trying to guess optimal parameters.