Update Json.NET library
Remove Async suffix on async method names.

Method names rename the same as the previous synchronous versions. This
generally deprecates synchronous http requests.
Replace usages of ExpectGet with SetupGet.

Moq has deprecated ExpectGet.
Update ViewOptions to use Stringbuilder
Remove usage of async void.

Async methods should always return a Task to ensure proper exception
handling and method composition with the TPL.
Use ConfigureAwait(false) for internal async / await calls.

This is really ugly, but considered good practice in an async API where we
don't know who our consumers are (e.g. WPF / ASP.NET). This shouldn't make
any difference to ASP.NET usage but, for UI consumers, this will prevent
deadlocks and unnecesary context mashalling.