Add title update feature

This pull request tried to solve issue #135.

I am not very familiar with this dashboard, there might be some title of pages in corner are not assigned. Please add those missing titles if you see one. It is simple, for example, to add a title to LoginRoute, just a `title` attribute like this

```
Balanced.LoginRoute = Balanced.Route.extend({
	title: 'Login',
	// ...
});
```

I have an i18n feature is under progress mentioned at issue #410. If you decide to continue on it, we may need to modify the way we set the title to support i18n feature.