copying over queue-api-redo branch from my 2012 repo

This commit is not cleanly separated from the next one where I got
everything to compile again (and possibly even further on from there).
diff --git a/aos/atom_code/camera/Buffers.h b/aos/atom_code/camera/Buffers.h
index 6b54188..07177bc 100644
--- a/aos/atom_code/camera/Buffers.h
+++ b/aos/atom_code/camera/Buffers.h
@@ -53,9 +53,8 @@
   // The current one. Sometimes NULL.
   const Message *message_;
   static const std::string kQueueName;
-  static const aos_type_sig kSignature;
   // NULL for the Reader one.
-  aos_queue *queue_;
+  Queue *queue_;
   // Make the actual mmap calls.
   // Called by Buffers() automatically.
   void MMap();