Remove preserveCas argument to set and add.
Remove preserveCas argument to set and add.

Also removed redundant add method, instead using a default value for
isDirty.

Change-Id: I4567a42f11c1dd1714dc17748dac7ce34d68b9f1
Reviewed-on: https://review.northscale.com:8443/1332
Reviewed-by: Dustin Sallings <1c08efb9b3965701be9d700d9a6f481f1ffec3ea@spy.net>
Tested-by: Dustin Sallings <1c08efb9b3965701be9d700d9a6f481f1ffec3ea@spy.net>

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