Dual license MIT/Apache 2.0, retroactively too [for codemirror-widgets]

It appears that https://github.com/SamyPesse/codemirror-widgets reused some of my code, and is Apache 2.0 licensed.
It's possible that was perfectly OK under MIT license, not sure.
In any case this will remove all doubts that yes, I'm happy to see it reused.

Author: cben

LICENSE

@@ -1,3 +1,9 @@
+Originally this project was MIT-licensed but I've changed it, *retroactively to all past versions*, 
+to be dual-licensed: you can use it under the MIT License (below), 
+or the [Apache License 2.0](https://www.apache.org/licenses/LICENSE-2.0).
+
+---------------------------------------------------------------------------------
+
 The MIT License (MIT)
 
 Copyright (c) 2013 Beni Cherniavsky-Paskin