Store full information about editors on Item
Editors are identified by three informations (userid, hostname, address). Discussed with mentor how to store a list of them, agreed to be in the form userid@hostname[address]. Created tests for methods that converts the dict with these information to this strings, and the opposite. Noted that Item's create method is failing. Created the conversion methods on items' Text class. Override Text's _save method to include this information on save.