WOW: add update.json

Add an update script, as suggested in #1499.

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Also, @jimaek, @Snoop and I were wondering over at https://github.com/matthieua/WOW/issues/103, how often the [website] gets updated? It seems that searching for WOW yields no results, however the CDN [already contains the file][cdn].

[website]: http://www.jsdelivr.com/
[cdn]: //cdn.jsdelivr.net/wow/1.0.1/wow.min.js