allow users to fully export their data

[François Marier]

A few notes on how this could work:

- "export your data" (new option) or "delete your account" would trigger the export (i.e. we always export before deleting someone's account)

- gearman job receives list of emails and the photo hashes that are in /user

- the export will contain a list of email addresses and a list of base64-encoded(?) photos. there's no point in storing the association between the two because the email addresses will need to be revalidated when the xml file is imported elsewhere.

- a link to the .xml.gz is returned to the user

- the filename will be a hash of username+password so that a double export will overwrite the previous one

- that .xml.gz file is kept for 1 day in /export (a cronjob deletes old exports)

- files in /user are deleted by a gearman job (created after the export is done) if the export happened as a result of "delete your account"

- permissions of /user can be changed to root-only writes since the webapp no longer needs to delete files from there

- the last point would also require photo deletion by users (i.e. removing the photo from /user) to be performed by a gearman job

Of course the next step will be to allow imports too :)

[François Marier (fmarier)]

User account export functionality is now live.