[sr-dev] ndb_redis module API

Hello, these three attached patches export an API from ndb_redis module. That API consists on three functions: + redisc_exec_f exec; + redisc_get_reply_f get_reply; + redisc_free_reply_f free_reply; exec function executes a redis command and attaches its response to a string. get_reply uses former response string to get a hiredis redisReply structure. free_reply deletes an unused response from local memory container. Regards, Vicente.