Add virtual function isKeyDumpSupported in CouchKVStore
Add virtual function isKeyDumpSupported in CouchKVStore

Change-Id: I2a8f14564cbb9f5f99b51258943ee4d817010d58
Reviewed-on: http://review.couchbase.org/14280
Tested-by: Jin Lim <c45cd80a556f432a3607171a6818cd5a074b5cd4@couchbase.com>
Tested-by: Junyi Xie <cec9b1c9f34a8d92cba938f3f3364d5120580782@gmail.com>
Reviewed-by: Junyi Xie <cec9b1c9f34a8d92cba938f3f3364d5120580782@gmail.com>

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