added chunk function and tests to arraybuffers

 * Adds a chunk function to ArrayBuffers
 * Adds arraybuffer-slice polyfill code for PhantomJS's lack of ArrayBuffer.slice  
 * Standardizes comments in ArrayBuffers to fit style
 * Adds a prepublish call to grunt
 * Adds comments to ArrayBuffers declaration file
 * Adds tests for concat and chunk interactions

TESTED: 
grunt

Note: this doesn't include a version bump, that will come in the next pull-request with a few more fixes.