Add projects (code and documentation) for .NET 4.5 build, update references where appropriate
Update IProgress<T> references for .NET 4.5 build
Update using statements to support ReadOnlyDictionary from .NET 4.5
Fix handling of location headers
Fix handling of the User-Agent header
Updated handling for the Content-Type header in requests
Updated integration tests to work with the new HttpClient-based implementation
Increase test timeout to mitigate some timeout failures
Remove and sort usings
Set upper limit on Newtonsoft.Json dependency