Change HTTPException to only take a single parameter.

discord/errors.py

@@ -57,15 +57,15 @@ class HTTPException(DiscordException):
 
     .. attribute:: text
 
-        The text of the response if it wasn't JSON. Could be None.
+        The text of the error. Could be an empty string.
     """
 
-    def __init__(self, response, message=None, text=None):
+    def __init__(self, response, message):
         self.response = response
-        self.text = text
+        self.text = message
 
         fmt = '{0.reason} (status code: {0.status})'
-        if message:
+        if len(message) < 100:
             fmt = fmt + ': {1}'
 
         super().__init__(fmt.format(self.response, message))