Adding a ReactiveNavigator to handle toActivityForResult in an Observable way

The aim of this component is to handle the navigation to an Activity for result using an Observable and thus avoiding the need to check for result/response code and all the boilerplate code related.
just wondering why `content`? That's Android's package for all things `ContentProvider`. Why not `app`, since that's where Android Context related things live? I think for the framework stuff, it would be helpful to resemble Android's package structure so that it's clear what these helpers relate to.