This patch does a couple things in preparation for publisher and subscriber code and cleaning up the replication API:
* Renames Applier to CommandApplier and Replicator to CommandReplicator. This makes it much clearer *what* is being applied or replicated...
* Establishes a Global Transaction ID typedef in ReplicationServices that other plugins and code can use. The upcoming CommandReader plugin API uses this typedef
* Updates the using namespace in all source files to be correct per style guidelines
* Converts pass-by-pointer to pass by reference and makes apply() and replicate() API calls const correct. Now, the only time pointers are passed in API calls is for pointer-to-base-class arguments.