The current router is passed to the current component via a binding.
To indicate that this is an angular provided object, this commit
renames the binding to `$router`.
BREAKING CHANGE:
The recently added binding of the current router to the current component
has been renamed from `router` to `$router`.
So now the recommended set up for your bindings in your routed component
is:
```js
{
...
bindings: {
$router: '<'
}
}
```
