prepended 'captcha:' for cache key to prevent confliction; set user to _global first whiling retrieving secret key from backend db, to work under distributed situation
prepended 'captcha:' for cache key to prevent confliction; set user to _global first whiling retrieving secret key from backend db, to work under distributed situation


git-svn-id: 1e305be66d043bb50495ad67d7451794839df690@1295 b2c27d59-8999-dc11-853b-000bcdefe56b

agentzh/old-openresty,agentzh/old-openresty,agentzh/old-openresty,beni55/old-openresty,beni55/old-openresty,agentzh/old-openresty,beni55/old-openresty,beni55/old-openresty,beni55/old-openresty