Remove asm.js-based simplex-noise for faster performance on Firefox

asm.js currently has a massive performance hit when crossing the
asm.js/JavaScript boundary, which happens on every simplex noise call,
so it is noticeably slower than pure JavaScript for chunk generation.
Revert to the 2.1.1 simplex-noise release (without asm.js) to fix this.

https://github.com/jwagner/simplex-noise.js/issues/5
Update dependencies
0.2.1