typo in SERVER_ERROR ascii error message prefix
typo in SERVER_ERROR ascii error message prefix

and, made some ascii error message strings have more uniform case.

Change-Id: I7ad8dbeaae71209cf240d82304d7e2237a87c69a

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