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.
this should be above this line: https://github.com/hazelcast/hazelcast-stabilizer/pull/441/files#diff-45fcd81646724cb9937e20c8eb2372f4R143