Rewrite as an ember-cli addon

Began 2.0 rewrite

This is the first step of many on the road to 2.0.

- [x] migrate existing code to ember-cli as an es6 modularized addon
- [x] add inline validators
- [x] remove prototype extension assumptions
- [x] add looking up of validators in multiple namespaces
- [x] replace all `object.get` with `get(object, ...`
- [x] replace all `object.set` with `set(object, ...`

The URL validator has been removed. It will be migrated to another addon that will add support for additional validators.