…nd require angular 8 peer dependencies

BREAKING CHANGE: uirouter core and rx packages are now `peerDependencies`.
You will need to explicitly install the correct versions of `@uirouter/core` and `@uirouter/rx` into your project.

before:

```
dependencies: {
  "@uirouter/angular": "4.0.0"
}
```

after (example -- versions will vary):
```
dependencies: {
  "@uirouter/angular": "5.0.0"
  "@uirouter/core": "6.0.1",
  "@uirouter/rx": "0.6.0",
}
```

Or, use this command to automatically install peerDependencies:

```
npx check-peer-dependencies --install
```

Ivy supports lazy loading of modules without depending on the ROUTES token from angular/router.

BREAKING CHANGE: UIRouter for Angular v6.0.0 now requires Angular 8 or higher

…ar/cli --next