Adding the Ability to Register a DeviceToken with the UA site

Liked your library and the way its written, but I needed a method of registering a Device Token so I could make sure device tokens are Active and change Inactive device tokens to active again when users reregister with the my application.

I just created a new PutRequest and DeviceTokenRequest classes, following your standards and a new DeviceToken dto class. I've also extended the Gateway class to have 2 methods which hide the calls to the DeviceTokenRequest.

Also would it be worth you creating a NuGet package and fleshing out more the API? There is nothing on NuGet last time I checked.