use bytearray rather than buffer for py3 compat

edosl0util/stream.py

@@ -133,8 +133,8 @@ class Packet(object):
             self.secondary_header.timecode.astimestamp() or None)
 
     def bytes(self):
-        return buffer(self.primary_header) + \
-            buffer(self.secondary_header) + self.data
+        return bytearray(self.primary_header) + \
+            bytearray(self.secondary_header) + self.data
 
     def is_group(self):
         return self.is_first() or self.is_continuing() or self.is_last()