Added IntIntMapTest and minor improvments

Added new IntIntMapTest to compare values with radargun benchmark.

Added new methods to KeyUtils.java for Integer keys.

Added new method addOperationRemainingProbability() to OperationSelector.java to add an operation which consumes the remaining probability.

Cleanup of bash scripts: update-stabilizer makes now use of $STABILIZER_HOME if set and uses maven to determine stabilizer version.
Copy/paste from StringMapTest.java. It's not used but wasn't marked as "unused" because its value was overwritten manually in the `main()` method o_O