-  authorized(+Action, +Options) is det
 - Verify that Action is authorized. Options:
- indentity(+Identity)
 - Indentity is the identity dict as collected by 
autenticate.pl. 
Actions defined:
- Gitty store actions
- gitty(download(Obj,Format))
 - Attempt to download Obj, one of 
file(File) or hash(Hash) in
Format, see storage_get/4 from storage.pl 
- gitty(create(File,Named,Meta))
 - Create file name File with the given meta-data. Named is one
of 
named or random and indicates whether the file is named
by the user or the name is generated by the system. 
- gitty(update(File,PrevMeta,Meta))
 - Update File and change meta-data from PrevMeta to Meta.
 
- gitty(delete(File,Meta))
 - Delete File that has the given meta data.
 
 
- File actions
- file(update(File,Meta))
 - Update (save) a physical file outside the versioned gitty
store.
 
 
- Social options
- chat(open)
 - Open websocket chat channel
 
- chat(post(Message,About))
 - Post a chat message about a specific topic
 
 
- throws
 - - 
http_reply(forbidden(URL)) if the action is not allowed. Can
we generate a JSON error object?