UMD module

Very useful library you guys created. I refactored the code to work as a UMD module. That way it can be loaded as an AMD module via require.js, as a common.js module under node, or like it was just globally via window.TextEncoder.

I had to merge the two files together into one file, which made sublime text a bit slow during development but the fact that it can be consumed by more environments should outweigh the cost.

Let me know what you think. Thanks