title: NativeScript + Mapbox pluggin: mapbox.show() error
body: <p>After a lot of try and error, trying to find a solution to <a href="http://%20%20[1]:%20https://stackoverflow.com/questions/48323880/nativescript-addmarkers-outside-of-onmapready/48325114#48325114" rel="nofollow noreferrer">this</a>, I understood thanks to help of Eddy Verbruggen that there two unique way to add markers to mapbox map: by code inside of onMapReady() or programmatically. </p>
  
  <p>But now, I find something that I can not solve: using exactly code indicated <a href="https://github.com/EddyVerbruggen/nativescript-mapbox/tree/26019957e4e3af3e737d7a44c845f5d5b1bfb808#declaring-a-map-programmatically" rel="nofollow noreferrer">Declaring a map programmatically</a>, when run the app appears errors originated in "TypeError: mapbox.show is not a function".</p>
  
  <p>The code is:</p>
  
  <pre><code>`var mapbox = require("nativescript-mapbox");
  var platform = require("platform");
  var isIOS = platform.device.os === platform.platformNames.ios;
  
  mapbox.show({
  accessToken: 'here i wrote my own API ACCESS TOKEN',
  style: street, 
  margins: {
    left: 40, // default 0
    right: 40, // default 0
    top: 450, // default 0
    bottom: isIOS ? 50: 0 
   },
  center: { // optional without a default
    lat: 52.3702160,
    lng: 4.8951680
  },
  zoomLevel: 9.25, 
  showUserLocation: true, 
  hideAttribution: false, 
  hideLogo: false, 
  hideCompass: false, 
  disableRotation: false,
  disableScroll: false,
  disableZoom: false, 
  markers: [ 
    {
      id: 1, 
      lat: 52.3732160, 
      lng: 4.8941680, 
      title: 'Nice location', 
      subtitle: 'Really really nice location', 
      icon: 'res://cool_marker', 
      selected: true, 
      onTap: function(marker) { console.log("This marker was tapped"); },
      onCalloutTap: function(marker) { console.log("marker was tapped"); }
    }
   ]
    }).then(
    function(showResult) {
      console.log("Mapbox show done for " + (showResult.ios ? "iOS" : 
   "Android") + ", native object received: " + (showResult.ios ? 
    showResult.ios : showResult.android));
    },
    function(error) {
      console.log("mapbox show error: " + error);
    }
  )`
  </code></pre>
  
  <p>To clarify, the app is build from "tns create my-app-name --template tns-template-blank". I only added nativescript-mapbox plugin and insert code indicate in "Declaring a map programmatically" inside on home.js file.</p>
  
  <p>I can't understand why appear that error, I'm sure that plugin was correctly installed. The app uses NS version 3.4.1 and nativescript-mapbox version 3.3.0, on Android.</p>