BUMP 2.7.3
post 2.7.3
SERVER-14135 implement processHandshake() in LegacyReplicationCoordinator
SERVER-14135 implement getElectionId() in LegacyReplicationCoordinator
SERVER-14135 implement waitUpToOneSecondForOptimeChange() in LegacyReplicationCoordinator
SERVER-14135 implement shutdown() in LegacyReplicationCoordinator
SERVER-14135 implement buildsIndexes() in LegacyReplicationCoordinator
SERVER-14135 implement getHostsWrittenTo() in LegacyReplicationCoordinator
 SERVER-14135 remove some usage of godMode and replSet bool from LegacyReplicationCoordinator
made a few comments
fixed merge conflicts
SERVER-14471 Fix build break with the Visual Studio 2013 Update 2 toolkit
SERVER-14471 Fixing lint error because of whitespace
Merge branch 'master' of https://github.com/mongodb/mongo into RocksDB
SERVER-14436 Remove dead ReplSetConfig::HealthOptions type.

It has no consumers.  The one instance is never changed or consulted.
SERVER-14460 Comment out implementation of checkReplicaMemberVersions for now
SERVER-14436 Introduce bsonCheckOnlyHasFields helpers.

These helpers paired with the bsonExtract helpers faciliate the manual parsing
of structures out of BSONObj.
SERVER-14299 prevent mongos from requesting unnecessary batches for sort + limit queries
SERVER-14460 Fix lint
first implementation of RocksBtreeImpl::advanceTo() and RocksBtreeImple::customLocate()