Notes be notes, even with pictures

Improvements for all users:

• Cozy Notes with photos will be exported as a tar archive instead of a simple
  markdown file. Therefore, the client will now unpack the markdown file from
  the archive when displaying a note in a degraded mode (i.e. when you're
  offline or the actual note can't be found on the remote Cozy).
• Error messages will now be properly localized and the document names included
  in some of them should be properly displayed instead of their type.

See also known issues.

Happy syncing!