Adding comments to define functionality of DcpStreamCtx & TestDcpConsumer
Adding comments to define functionality of DcpStreamCtx & TestDcpConsumer

Context: tests/ep_testsuite_dcp.cc

Change-Id: I162816fec76f4efdcacfa0463bbb3892b3b802e5
Reviewed-on: http://review.couchbase.org/60273
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Chiyoung Seo <fcffc23db27b19ee4ebba46695ee6b50e09216a2@couchbase.com>

hisundar/ep-engine,owendCB/ep-engine,couchbase/ep-engine,owendCB/ep-engine,membase/ep-engine,couchbase/ep-engine,teligent-ru/ep-engine,daverigby/ep-engine,daverigby/kv_engine,daverigby/ep-engine,couchbase/ep-engine,membase/ep-engine,owendCB/ep-engine,teligent-ru/ep-engine,couchbase/ep-engine,teligent-ru/ep-engine,daverigby/ep-engine,hisundar/ep-engine,daverigby/kv_engine,hisundar/ep-engine,owendCB/ep-engine,daverigby/kv_engine,teligent-ru/ep-engine,daverigby/ep-engine,membase/ep-engine,daverigby/kv_engine,membase/ep-engine,hisundar/ep-engine