key_creator: return key class, not instance (remove repository arg)

attic/archiver.py

@@ -57,7 +57,8 @@ class Archiver:
         """Initialize an empty repository"""
         print('Initializing repository at "%s"' % args.repository.orig)
         repository = self.open_repository(args.repository, create=True, exclusive=True)
-        key = key_creator(repository, args)
+        key_cls = key_creator(args)
+        key = key_cls.create(repository, args)
         manifest = Manifest(key, repository)
         manifest.write()
         repository.commit()

attic/key.py

@@ -734,13 +734,13 @@ def compressor_creator(args):
     return compressor
 
 
-def key_creator(repository, args):
+def key_creator(args):
     if args.encryption == 'keyfile':
-        return KeyfileKey.create(repository, args)
+        return KeyfileKey
     if args.encryption == 'passphrase':
-        return PassphraseKey.create(repository, args)
+        return PassphraseKey
     if args.encryption == 'none':
-        return PlaintextKey.create(repository, args)
+        return PlaintextKey
     raise NotImplemented("no encryption %s" % args.encryption)