Upgraded project to .NET 4.0 and reinstalled OAuth nuget package
Merge pull request #141 from gregsochanik/dotnet4

Upgraded project to .NET 4.0 and reinstalled OAuth nuget package
Removed unused internal tests
Merge pull request #142 from gregsochanik/remove-internal-tests

Removed unused internal tests
Set requestBody to string.empty by default to reduce some code
Small refactor reducing a couple of lines of code
Issue #106 - Decided just to remove the comment from this field as the xml response is nullable xsi:nil="true"
Added a RequestPayload class, and added WithPayload option to FLuentApi and test, which currently does nothing