Load redis client and ensure that is passed to plugins.

  The object that is passed to the plugins will have a redis-member.
  Use redis for caching purposes.

  If the sfs-plugin finds spam it will add a redis-key to mark
 that as spam for the next 48 hours, the ip-plugin will lookup
 that value to terminate testing early.
  Resync.  We keep state now.
  Added plugin to validate MX for emails.