Implement `Router.prototype.resolve(method, path)` Fixes #2
Cleanup

- Rename `Router.prototype._resolveCallback` to `_parseCallback`
- Rename `src/ergo.js` to `src/Router.js`
- Rename `test/test.js` to `test/Router.js`
- Reword and refactor a few tests
Merge branch 'fix2'
Add documentation of `Router.prototype.resolve(method, path)`
Cleanup tests

I'm trying to workout a good style. Any suggestions?