add github support, fix redirect on oauth

realms/modules/auth/oauth/models.py

@@ -17,6 +17,16 @@ providers = {
             authorize_url='https://api.twitter.com/oauth/authenticate',
             access_token_method='GET'),
         'button': '<a href="/login/oauth/twitter" class="btn btn-default"><i class="fa fa-twitter"></i> Twitter</a>'
+    },
+    'github': {
+        'oauth': dict(
+            request_token_params={'scope': 'user:email'},
+            base_url='https://api.github.com/',
+            request_token_url=None,
+            access_token_method='POST',
+            access_token_url='https://github.com/login/oauth/access_token',
+            authorize_url='https://github.com/login/oauth/authorize'),
+        'button': '<a href="/login/oauth/github" class="btn btn-default"><i class="fa fa-github"></i> Github</a>'
     }
 }
 
@@ -69,8 +79,8 @@ class User(BaseUser):
 
     @staticmethod
     def login_form():
-        buttons = ''
+        buttons = []
         for k, v in providers.items():
-            buttons += v.get('button')
+            buttons.append(v.get('button'))
 
-        return buttons
+        return " ".join(buttons)

realms/modules/auth/oauth/views.py

@@ -16,7 +16,7 @@ def login(provider):
 
 @blueprint.route('/login/oauth/<provider>/callback')
 def callback(provider):
-    next_url = request.args.get('next') or current_app.config['ROOT_ENDPOINT']
+    next_url = request.args.get('next') or url_for(current_app.config['ROOT_ENDPOINT'])
     try:
         resp = User.get_app(provider).authorized_response()
         if resp is None: