Eat your vegetables - Broccolification

OK, so this is my stab at #93. Building the different versions (AMD, CommonJS, standalone) via `broccoli build dist` is now possible. This is my first time using Broccoli so the `Brocfile.js` is kind of a mess and looks accordingly. I am sure that there is place for improvements so keep the feedback coming!

I [changed](https://github.com/pangratz/router.js/commit/f369b721cc490491222b0437a5135a74a76f4a0c) the import statements in `lib` and `test/tests`, so they are relative now. This can be extracted into a separate PR I guess ...

There is still an issue which needs to be resolved: The contents of `dist/router.js`, `dist/router.amd.js` using `broccoli` are the same like the ones, using `grunt build` before. But it seems that the CommonJS version in `dist/commonjs` now includes more files than before: `dist/commonjs/router/handler-info/*` and `dist/commonjs/router/transition-intent/*`. I don't know, but have they been "forgotten" in previous builds or should they not be there?

I leave some comments in the `Brocfile.js` where I'm uncertain how stuff can be handled better ...

:deciduous_tree:

TODO

- [ ] simplify `Brocfile.js`
- [ ] add some documentation to the README