Update LICENSE.md to include license information about Mousetrap.

LICENSE.md

@@ -55,6 +55,22 b' It is Copyright 2013 jQuery Foundation a'
 
 
 
+Mousetrap
+---------
+
+Kallithea incorporates parts of the Javascript system called
+[Mousetrap](http://craig.is/killing/mice/), which is:
+
+   Copyright 2013 Craig Campbell
+
+and licensed under
+[the Apache License 2.0](http://www.apache.org/licenses/LICENSE-2.0.html).
+
+A [copy of the Apache License 2.0](Apache-License-2.0.txt) is also included
+in this distribution.
+
+
+
 Mergely
 -------