Change validators to use the validator_context

Change InstanceKeys to take a namedtuple for context

util/config/validators/validate_ssl.py

@@ -8,8 +8,9 @@ class SSLValidator(BaseValidator):
   name = "ssl"
 
   @classmethod
-  def validate(cls, config, user, user_password, app):
+  def validate(cls, validator_context):
     """ Validates the SSL configuration (if enabled). """
+    config = validator_context.config
 
     # Skip if non-SSL.
     if config.get('PREFERRED_URL_SCHEME', 'http') != 'https':