SERVER-15089 remove fatal state and refactor rollback to use replcoord
SERVER-15255 fix unit test
SERVER-15195 Implement getHostsWrittenTo in ReplicationCoordinatorImpl
SERVER-14567 Implement checkIfWriteConcernCanBeSatisfied in ReplicationCoordinatorImpl
SERVER-14445 Remove waitUpToOneSecondForOptimeChange from ReplicationCoordinator
SERVER-15248 Introduce ScatterGatherAlgorithm interface and ScatterGatherRunner.

The ScatterGatherAlgorithm interface describes operations that a scatter-gather
process must perform.  ScatterGatherRunner uses a ReplicationExecutor to
execute a ScatterGatherAlgorithm.
SERVER-13635: make generic SortedDataInterface unit test
SERVER-15247 GroupCommand::parseRequest() read CodeWScope correctly
SERVER-14444 Implement stepDown functionality in RelicationCoordinatorImpl
SERVER-14600 rename canServeReadsFor() to checkCanServeReadsFor() in the ReplicationCoordinator
SERVER-14102 made good progress but still lots to do
SERVER-14102 moved out to own file