Fixed bug in SyntheticBackPressureTest when backupdelaynanos is 0
#383
OperationSelector implemented.

It's now possible to register operations to be selected with various probabilities without worrying about algorithm behind it.
A worker can just use the selector without knowing about probabilities at all.
Merge pull request #399 from hazelcast/improvements/operation-selector

OperationSelector implemented
Commented out code causing compilation problems
Commented out code causing compilation problems
Enabled the jcache tests again and bumped HZ version to 3.4-RC1-SNAPSHOT
Added logging of partition distribution