Log Improvements and Minor fixes

- No need to use hostname in NewMutationStreamReader(stream_reader.go)
- Shutdown command from supervisor needs to have sync response
(admin_manager, timekeeper, cluster_manager_sender)
- Add perf counter to stream reader(stream_reader.go)
- Better default values for constants
- Improve logging

Change-Id: Ia21250a4f817d239c5a2d37aa0a7771a8e04992b
Reviewed-on: http://review.couchbase.org/39162
Reviewed-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>
Tested-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>