VTGate V2 implementation and sandbox test improvement
Merge branch 'master' into liguo

Conflicts:
	go/vt/vtgate/proto/vtgate_proto.go
Update VTGate V2 with keyspaceid and keyrange queries
Merge branch 'master' into liguo, generate additional bson files

Conflicts:
	go/vt/key/key.go
	go/vt/vtgate/proto/vtgate_proto.go
	go/vt/vtgate/scatter_conn_test.go
	go/vt/vtgate/shard_conn_test.go
EntityIdsQuery related change (WIP)
Merge branch 'master' into liguo
Address comments
Merge branch 'master' into liguo