1. tunable log level per replication
2. pipeline supervisor
Merge branch 'master' of
https://github.com/Xiaomei-Zhang/couchbase_goxdcr_impl

Conflicts:
	base/constant.go
	factory/xdcr_factory.go
	metadata/replication_settings.go
	parts/xmem_nozzle.go
	protobuf/replication.go
	replication_manager/adminport.go
	replication_manager/replication_manager.go
	tests/factory/factory_run.go
	tests/pipeline/xdcr_pipeline.go
	utils/utils.go
merge