Add Batman.js 0.15.0

Adds Batman.js 0.15.0 (latest) to cdnjs. I wasn't sure where I could get the 0.15.0 build easily (hence the PR), so I checked out [the 0.15.0 tag](https://github.com/batmanjs/batman/releases/tag/v0.15.0) and ran `cake build:dist`. Included here is the `batman.min.js` that resulted from that! 

Thanks a lot, and if this works out, I'll probably add a couple of the near-depencies (rails driver, jquery driver) too. Does it look ok?