Remove unnecessary abort in CouchKVStore
Remove unnecessary abort in CouchKVStore

Removed abort calls that were mainly added for debugging
(other than obvious ones). Replaced them with better
error return instead.

Change-Id: I0894f19b58e04a979b0bc16c78d176537502929a
Reviewed-on: http://review.couchbase.org/14589
Reviewed-by: Junyi Xie <cec9b1c9f34a8d92cba938f3f3364d5120580782@gmail.com>
Tested-by: Jin Lim <c45cd80a556f432a3607171a6818cd5a074b5cd4@couchbase.com>

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