Allow more Trello settings

docs/backends/trello.rst

@@ -12,5 +12,15 @@ In order to enable it, follow:
     SOCIAL_AUTH_TRELLO_KEY = '...'
     SOCIAL_AUTH_TRELLO_SECRET = '...'
 
+There are also two optional settings:
+
+- your app name, otherwise the authorization page will say "Let An unknown application use your account?"::
+
+    SOCIAL_AUTH_TRELLO_APP_NAME = 'My App'
+
+- the expiration period, social auth defaults to 'never', but you can change it::
+
+    SOCIAL_AUTH_TRELLO_EXPIRATION = '30days'
+
 
 .. _Trello Developers API Keys: https://trello.com/1/appKey/generate

social/backends/trello.py

@@ -38,3 +38,10 @@ def user_data(self, access_token):
             return self.get_json(url, auth=self.oauth_auth(access_token))
         except ValueError:
             return None
+
+    def auth_extra_arguments(self):
+        return {
+            'name': self.setting('APP_NAME', ''),
+            # trello default expiration is '30days'
+            'expiration': self.setting('EXPIRATION', 'never')
+        }