Refactor app to use new version of router

## Refactor app to use new version of router

### Acceptance Criteria
1. App works the same.
1. New version of router is used.

### Tasks
- Implement [react-router](https://github.com/rackt/react-router) 0.7.0
- Add nesting where appropriate

### Additional Notes
- None
Pull this else onto the end of the last line:

```JavaScript
if (...) {
    // ...
} else {
    // ...
}
```