remove _lastPurgedGTID and _lastPurgedTS
remove remnants of lastPurgedGTID and lastPurgedTS from heartbeats.

With partitioned collections, we don't care about this data

remove some TODOs
remove partition comment
 - disable renaming
 - get convertToPartitioned working
 - support upgrade of non-partitioned oplog and oplog.refs to partitioned
fix bug
disable replication of partitioned collections
fix bug in writing oplog stuff to secondaries
add simple test that shows cloning of oplog works
add test showing partitioned collections don't work in replication