Merge remote-tracking branch 'origin/pr/79'
Make custom SSL verification optional

This affects perf, so only enable it if the user asks
Cancel everything happening in the progress stream if the token fires
ReadAsByteArrayAsync is fundamentally uncancelable, use a cancelling version
Build using SDK 8.0
Implement certificate verification on iOS
Copy-paste in the cert callback from Android
Add custom SSL verification to facade
Merge pull request #81 from paulcbetts/ios-cert-validation

Ios cert validation
Dumb mistakes are dumb
Version bump to 2.1.0
Add Xamarin.iOS 64-bit solution
Update NSUrlSessionHandler to handle nint StatusCode
Merge pull request #82 from paulcbetts/xamarin-64

Xamarin 64-bit support
Fix NuGet profile name
Version bump to 2.1.1
Update the Makefile for Xamarin.iOS 64-bit
Added iOS64 Unified API Sample
Copied from the existing Classic API Sample, with the necessary changes to compile under Unified API
Component packaging updated for iOS64 Unified API
Added ios-unified definition to the component.yaml, as well as the Unified Sample
Updated xamarin-component.exe to deal with new library platform target ios-unified
Fixed iOS64 Unified API Sample's reference to the actual lib