[ADDITION] Rate limiting requests

 * Adds the ability to limit the number of requests from the same IP down to X requests per Y time
 * Uses Memcache; no DB hits
 * This should cut down on some of the resource intensive pages being abused
 * Defaults protect everything and limit requests to 30 per 1 minute
 * THIS IS EXPERIMENTAL AND NOT FINISHED YET
 * That about covers it.
   * Needs to be tested to ensure it doesn't kill Memcache on larger installs