Simplified UMD header.
Simplified UMD header.

- Removed `System.register()` call. SystemJS treats this as an AMD module and applies AMD shim anyway.
- Moved AMD `define()` call ahead of `module.exports` assignment.
- `require()` only needs to hold the exported value for each module.

joshuabrown-ellation/libjass,Arnavion/libjass,joshuabrown-ellation/libjass,Arnavion/libjass,Arnavion/libjass,joshuabrown-ellation/libjass