Partial implementation of mock_store_t.
Merge branch 'sam_803' into sam_803_dummy
Implemented mock_store_t::read and mock_store_t::write.
Made mock_store_t have a notion of timestamps.
Added mock_store_t::send_backfill and receive_backfill.
Implemented mock_store_t::reset_data.
Removed "= 0" on mock_store_t::reset_data.
Fixed up last apparent problems with mock_store_t implementation and made ClusteringBackfill unit tests use mock_store_t.
Made test_cluster_group_t not be templatized (with its false templatization).
Revert "Made test_cluster_group_t not be templatized (with its false templatization)."

This reverts commit 42597c9fd7199805f42c5ff124632811765bc129.
Revert "Revert "Made test_cluster_group_t not be templatized (with its false templatization).""

This reverts commit b796daaa74a54dd2f8b2598859e36931ca9e5a76.
Some changes in support of soon changing test_cluster_group_t over to mock stores and rdb_protocol_t.
Switched the test_cluster_group_t over to rdb_protocol_t and mock_store_t.  Maybe broken.
Passed NULL for rdb_protocol_t::context_t in test_cluster_group, fixed mock_parse_read_response bug, ClusteringReactor test passes.
Fixed mock_parse_read_response logic to handle R_NULL, which is what the point_read_response_t has instead of an empty datum pointer.
Merge branch 'sam_803' into sam_803_dummy
Removed DummyProtocolNamespaceInterface test (it is redundant with RdbProtocol test, really).
Made the ClusteringSuggester tests use the rdb protocol.
Made the RegionMap tests use the rdb protocol.
Got ClusteringBranch switched over _except_ that the NULL context_t is bad.