Fix bug with forEach, improve build process, add regex for Silk on Android.

This Pull request addresses a few things:

First of all, it fixes a bug with the `each`/`forEach` utility function.

This also improves the build process so that minification, beautification, etc. is included in the 'build/build.js' script.  The script also now allows input from a specified file and output to a specified file.  I'm not sure how the build process was done before, but the goal is to provide all the tools necessary for building a release within the repo itself.

Finally it adds a regex for Silk on Android (pulled from the [ua-parser library](https://github.com/tobie/ua-parser)).  I think there should probably be a process for keeping the regexes in this repo in sync with the ua-parser ones.