Add abilty to create VTPK's

[marikavertzonis]

Here are the esri vector basemaps https://www.arcgis.com/home/group.html?id=30de8da907d240a0bccd5ad3ff25ef4a#overview

Add abilty to create VTPK's in Tile Package Kreator.

Note: Consider that once you download an area, you should be able to apply a different stylesheet to it, to change its appearance (eg: you can switch between dark background and regular streetmap with just the change of a stylesheet). You shouldn't need to download / save / store a second VTPK for the same tile area. There should be a way to add additional style sheets to an existing VTPK. eg: you create a VTPK with the default stylesheet. you then select that VTPK and update it with the dark background style sheet. Tomorrow you might decide to add the light grey one to it too.