Adding support for Telus

Telus has strange issues with MMS headers, so this handles it.

src/mmsutil.c

@@ -735,7 +735,7 @@ static header_handler handler_for_type(enum mms_header header)
 		return NULL;
 	}
 
-	return NULL;
+	return -1;
 }
 
 struct header_handler_entry {
@@ -784,6 +784,11 @@ static gboolean mms_parse_headers(struct wsp_header_iter *iter,
 			DBG("no handler for type %u", h);
 			return FALSE;
 		}
+		/*  Telus has strange headers, so this handles it */
+        if (handler == -1) {
+           DBG("type isn't a part of the standard? Skipping %u", h);
+           continue;
+        }
 
 		DBG("saw header of type %u", h);