Fix logger names

Author: rayluo

oauth2cli/assertion.py

@@ -7,7 +7,7 @@
 import jwt
 
 
-logger = logging.getLogger(__file__)
+logger = logging.getLogger(__name__)
 
 class Signer(object):
     def sign_assertion(

oauth2cli/authcode.py

@@ -21,7 +21,7 @@
 from .oauth2 import Client
 
 
-logger = logging.getLogger(__file__)
+logger = logging.getLogger(__name__)
 
 def obtain_auth_code(listen_port, auth_uri=None):
     """This function will start a web server listening on http://localhost:port