Modified get_normalized_parameters so it does not encode '~' for full conformance with RFC 5849 section 3.6

Author: hbs

oauth2/__init__.py

@@ -369,7 +369,7 @@ def get_normalized_parameters(self):
         # spec draft 7, section 3.6
         # (http://tools.ietf.org/html/draft-hammer-oauth-07#section-3.6)
         # Spaces must be encoded with "%20" instead of "+"
-        return encoded_str.replace('+', '%20')
+        return encoded_str.replace('+', '%20').replace('%7E', '~')
 
     def sign_request(self, signature_method, consumer, token):
         """Set the signature parameter to the result of sign."""