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: '<'
  }
}
```

@petebacondarwin deserves credit for most of this commit.

This allows you to specify a regex and serializer function instead
of the path DSL in your route declaration.

```
@RouteConfig([
  { regex: '[a-z]+.[0-9]+',
    serializer: (params) => `{params.a}.params.b}`,
    component: MyComponent }
])
class Component {}
```

Closes angular#7325
Closes angular#7126