avoid double encoding on import from exported file
added authorship to dreams (only via import for now)
- added dream authorship in dream form

- restricted access to dream edition/deletion for author and admins

- error handling for user without any dreamer

- corrected a bug in the use of levenshtein distance
ability to reassign every dream of a dreamer to a user (useful after a CSV import)
small correction on warning display
- FIX: encoding problem on tags during import due to unnecessary lowercase transformation

- emptying the link between dreamers and users when deleting dreamers on import
added a warning message for CSV import
- multiple FIX on import/export of tags and author

- added an 'app key' for the public RSS feed, to avoid unwanted access