Implemented Perlin noise

I ported perlin noise exactly from [PApplet.java](https://github.com/processing/processing/blob/master/core/src/processing/core/PApplet.java).  As far as I can tell it works as expected.  My unit test is nothing great, just checks to make sure we get a number between 0 and 1.  Also, seeding has not been implemented yet.  Finally, I'm not 100% sure I incorporated the new noise.js file correctly.  

I'm more than happy for someone to look this over and tell me I'm doing things wrong.