Update TODO

TODO.md

@@ -4,7 +4,7 @@
 * communicator/ssh: Ability to re-establish connection
 * communicator/ssh: Download()
 * packer: Communicator should have Close() method
-* packer: RemoteCommand.ExitChan() should be more efficient
+* packer: Pretty unhappy with RemoteCommand... should discuss improvement
 * packer: Ui input
 * packer/plugin: Better error messages/detection if plugin crashes
 * packer/plugin: Testing of client struct/methods