Added NuGet dependency on Microsoft.Bcl.Async for WebRequest.GetResponseAsync() & friends.
Replaced two BeginGetRequestStream instances.
Refactored two WebRequest.BeginGetResponse(...) instances.
Merge pull request #2 from dlhartveld/refactor-apm-to-aa

Replacement of APM usage (Begin/EndGetResponse, etc.) with TAP (GetResponseAsync) and async/await