* due to server bugs, some offline buddies are still notified on publication,
  causing error reply, that pep accepts as event. check message type/presence of error tag.
* check input/output for validity, where applicable
* extract common code into one place
* add avatar
  * pep_avatar, avatar_cache, avatar, aavatar (separate)
    * in
      * !avatar-metadata-in        @ pep_avatar  
      * symbol-resolved request    @ avatar_cache  
      * !avatar-data-in            @ pep_avatar  
      * !avatar-in (file)          @ avatar_cache
      * print, printaa             @ avatar, aavatar
    * out
      * avatar_cache     calculates hash and saves hash to cache(, links jid to hash?)
      * avatar_cache     !avatar-data-out
      * pep_avatar       sends data
      * pep_avatar       reports error/notify of success (does static handler have node info?)
      * avatar_cache     gets file from cache, calculates metadata, !avatar-metadata-out
      * pep_avatar       sends metadata
      * pep_avatar       reports error/(notify of success?)
      * avatar_cache     (links jid to hash?)
  * handle url avatars (curl)
  * report absence of avatar