Point describe async at describe resource

Switch the DescribeAsync call to point at the documented Describe URL, added a GetBasicInformationAsync to call the Basic Information resource that Describe Async was previously calling. Added some unit tests that can be easily extended to cover the authorization failure cases that are currently' TODO'd in the library without having to call out to an external resource (works locally in NCrunch and VS, hope CI likes them). Added a functional test for the new BasicInformation call.