More async io for ASCII protocol
More async io for ASCII protocol

Added support for stats, delete and flush_all

daverigby/kv_engine,owendCB/memcached,couchbase/memcached,Metaswitch/memcached,mrkwse/memcached,Metaswitch/memcached,couchbase/memcached,daverigby/memcached,Metaswitch/memcached,cloudrain21/memcached-1,daverigby/kv_engine,abhinavdangeti/memcached,mrkwse/memcached,mrkwse/memcached,cloudrain21/memcached-1,daverigby/memcached,daverigby/memcached,zbase/memcached,zbase/memcached,zbase/memcached,daverigby/kv_engine,owendCB/memcached,abhinavdangeti/memcached,owendCB/memcached,cloudrain21/memcached-1,Metaswitch/memcached,couchbase/memcached,abhinavdangeti/memcached,jimwwalker/memcached,cloudrain21/memcached-1,daverigby/kv_engine,jimwwalker/memcached,daverigby/memcached,owendCB/memcached,jimwwalker/memcached,abhinavdangeti/memcached,Metaswitch/memcached,zbase/memcached,couchbase/memcached,mrkwse/memcached,abhinavdangeti/memcached,zbase/memcached