Update API for v4 of LaunchNavigator plugin

[dpa99c]

I've just published v4 of phonegap-launch-navigator which is a major rewrite of the plugin.

Amongst other things, it makes backwardly-incompatible changes to some of the API (the options passed to navigate()), as well as adding new options and API functions.

I will try to get around to making a pull request to update the Ionic Native wrapper, but in case I don't have time, this issue captures it.

The bundled typings have been updated for v4 and can be used for reference.