notification support

Each time `AppCop` is making action it should push notification message, stating what app was action commenced on.

We should use JSON format and send HTTP POST to specified endpoint where some message broker should intercept it (e.g [Hermes](https://github.com/allegro/hermes)).

Example message:

```
{
"timestamp": "1970-01-01T00:00:00+00:00",
"appID": "com.example.testApp",
"Action": "scaleDown"
}
```

Notifications should be disabled by default via config.