Added NativeScript examples

[triniwiz]

A simple chat app example of how to integrate Horizon with a NativeScript or NativeScript + Angular 2

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This change is

[deontologician]

This is awesome, thanks for the PR. We will probably be able to check it out next week

[dalanmiller]

@triniwiz I attempted to get some of your examples going but had trouble getting them started. I should be able to go into either of the new folders run hz init and then hz serve --dev and see the app at localhost:8181 correct?

[triniwiz]

In the examples i presume the user is familiar with nativescript and has it installed on their system already so all they will need to do is install rethinkdb + horizon

hz init nschatApp
cd nschatAPP
hz serve --dev  --allow-unauthenticated true --auto-create-collection true --auto-create-index true

git clone https://github.com/rethinkdb/horizon/examples
cd horizon-nativescript-chat-app
npm i

tns run android or tns run ios

[mglukhovsky]

@dalanmiller, have you gotten a chance to review this example yet?