fixes #2112
 subsequent proxy creations on same name should wait eachother
clean up
* Fixed backup loss issue during graceful shutdown.
* Improved replica sync retry process.
* Refactored partitioning code.
executor clean up and adding tests for coverage
executor clean up and adding tests for coverage
executor clean up and adding tests for coverage
executor clean up and adding tests for coverage
Merged PR #2136
Merge branch 'fix/3.3/partition' of github.com:mdogan/hazelcast
Merge pull request #2153 from pveentjer/operation-service-cleanup

Operation service cleanup
Merge pull request #2155 from Danny-Hazelcast/clientExecutor

Client executor
Simplification in callbacks
Integrated the Remotecall object into the Invocation to simplify +
reduce object litter.
Removed remotecallback
Fixed bug when callback runs into a shutdown asyn executor