Android.Proximity: Conflicts with foreign Gson and Kotlin dependencies

[drietz]

For example when using Mapbox nuget packages together with Estimote.Proximity in Android projects, there are build errors stating, that some classes already have been added (e.g. "Lkotlin/ArrayIntrinsicsKt").

I would like to suggest replacing Kotlin and Gson jars with their respective NuGet packages, which are available from Microsoft.