Switch to CommonJS modules and browserify build

*Feedback is welcome*

This is the start of work towards a 1.0.0 release. I've split the code into a set of initial modules and use browserify to build the library. Further work is needed to make this the only client for Node and the browser.

**Build System**
I'm using Gulp to build the library and sourcemaps.

**Changes**
I upgraded to JSON3. This fixes #123 and #160.

**Tests**
I've ensured that all tests continue to pass on latest Chrome, Firefox, Safari, and IE. I'm trying to get Travis CI to run browser testing on every push, but I'm still working on that.