GUACAMOLE-773: Add license information for new JavaScript dependencies pulled in by Webpack.

doc/licenses/assert-1.5.0/README

@@ -0,0 +1,8 @@
+assert (https://github.com/browserify/commonjs-assert/)
+-------------------------------------------------------
+
+    Version: 1.5.0
+    From: 'Joyent, Inc. and other Node contributors'
+    License(s):
+        MIT (bundled/assert-1.5.0/LICENSE)
+