DEV: Make login a base-class default on Authenticator.get_handlers.

Rather than a module-level default.  Makes it easier for custom
Authenticators to unmount /login.

jupyterhub/auth.py

@@ -12,6 +12,7 @@ import simplepam
 from IPython.config import LoggingConfigurable
 from IPython.utils.traitlets import Bool, Set, Unicode
 
+from .handlers.login import LoginHandler
 from .utils import url_path_join
 
 class Authenticator(LoggingConfigurable):
@@ -70,7 +71,9 @@ class Authenticator(LoggingConfigurable):
         
         (e.g. for OAuth)
         """
-        return []
+        return [
+            ('/login', LoginHandler),
+        ]
 
 class LocalAuthenticator(Authenticator):
     """Base class for Authenticators that work with local *ix users
@@ -156,4 +159,4 @@ class PAMAuthenticator(LocalAuthenticator):
         bpassword = data['password'].encode(self.encoding)
         if simplepam.authenticate(busername, bpassword, service=self.service):
             return username
-    
+