SERVER-12119 Add new command to allow applications to append notes to the oplog
SERVER-12139 get rid of verbose log line in debug sharding
SERVER-12139 allow BSONElement parsing for single-pass parse speedup
SERVER-12139 refactor bulk write op processing in batch write ops

Pushes bulk writes under a single write lock acquisition, cleanup of
preprocessing.
Merge remote-tracking branch 'upstream/master'