Add more documentation to the code and some cleanup
Add more documentation to the code and some cleanup

Change-Id: I37ae7295cf49e8b47647d39cce4ad3276c1efafc
Reviewed-on: http://review.membase.org/6401
Tested-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@gmail.com>
Reviewed-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>

membase/bucket_engine,membase/bucket_engine,couchbase/bucket_engine,couchbase/bucket_engine,membase/bucket_engine,couchbase/bucket_engine,couchbase/bucket_engine,membase/bucket_engine