Added "with" statement feature to the BytesBuffer (used to lock the buffer).

sjrpc/utils/datastructures.py

@@ -63,3 +63,9 @@ class BytesBuffer(object):
         '''
         
         return len(self._buf)
+
+    def __enter__(self):
+        return self._lock.__enter__()
+
+    def __exit__(self):
+        return self._lock.__exit__()