Remove None values from sig generation

src/authenticator/official.py

@@ -28,6 +28,8 @@ def get_sig(method, values, secret):
 	""" Create a signature for parameters passed to VK API. """
 	postdata = ""
 	for key in values:
+		# None values should be excluded from SIG, otherwise VK won't validate it correctly.
+		if values[key] != None:
 			postdata = postdata + "{key}={value}&".format(key=key, value=values[key])
 	# Remove the last "&" character.
 	postdata = postdata[:-1]