This commit introduces changes to the user data export archive format.
This extends data set which is included in the archive. This data can be
then imported to other pods when this feature is implemented.
Also the commit adds the archive format json schema. ATM it is used in
automatic tests only, but in future it will also be used to validate
incoming archives.
Also:
* remove ShareablesFromPerson evil-query
* improve multi-stream and aspect-stream queries
* fix logging for recieve
* don't add last 100 public posts to users streams after sharing
* delete share visibility when shareable is deleted
* Wrap it into a transaction
* Use destroy over delete so dependent destroys get triggered
and we thus don't fail on the foreign key constraits
* Check if a photos status message actually exists before accessing
it
* Add missing dependent destroys
