Namespace and Composer Package

Hey, thanks for a useful class.  I just wanted to suggest adding a namespace to this library and making it a Composer package (preferably posted to Packagist) for easier discovery.  The changes could look something like this.  The tests would of course need some minor changes to work with the namespace.  I left that out since I wasn't sure if maybe you'd want the tests to assume auto-loading in addition to making that needed change.