Implemented get_stats test.
Implemented get_stats test.

Change-Id: I06cf456fd63343635da72546d4c83a7848d5c7ce
Reviewed-on: http://review.northscale.com/2886
Tested-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>
Reviewed-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>

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