Refactored to remove UriSigner.

In order to do this I had to invert a switch statement that selected which `RequestHandler` to use based on the current request Method, so now the `RequestCoordinator` ctor signature has changed to take an `IEnumerable<RequestHandler>`. (https://github.com/gregsochanik/SevenDigital.Api.Wrapper/compare/crenna-oauth?expand=1#diff-80302ed9266f92bd2e22a9a34809bb66R25)

This may cause a breaking change to the way you instantiate an instance of `FluentApi`, but if you're using a decent IoC framework you shouldn't have a problem.

I've included a static `RequestHandlerFactory` that sets up the concrete `GetRequestHandler` and `PostRequestHandler`s for now.

This work is necessary not only for making replacing the OAuth code with the http://www.nuget.org/packages/OAuth/ library, but also in order to support requesting the Api with non GET and POST verbs in the future.

The Locker Test changes are to a dummy locker I created with a Token and Secret that I haven't committed. It checks for the existance of the TEST CONTENT dummy release.