Stop eating the error detail.

Some APIs return useful messages in 401 responses, etc, but
HttpResponseMessage.EnsureStatusCode() throws away the response, and
only includes the status code in the message of the exception it throws.

This throws a custom ApiException with enough information in it to deal
with the error properly.
Added integration test which uses custom exception.

Had to modify the PostToRequestBin test too, but I'm not sure what the
point of that is since it will always fail. Maybe we should just remove
it?
Support for urlencoded form posts.
Handle exceptions when reading error content.
adds custom Json result converters in tests to demo functionality
refactored for cosistency with the current project styles
Merge remote-tracking branch 'origin/pr/45'
Merge remote-tracking branch 'origin/pr/48'

Conflicts:
	Refit-Tests/RestService.cs
Merge remote-tracking branch 'origin/pr/46'

Conflicts:
	Refit-Tests/RequestBuilder.cs
	Refit/RequestBuilderImplementation.cs
Fix up JSON.NET references to point at NuGet
Fix up the tests to use correct JSON.NET too
Fix up tests
Fix up npm.js paths
Fix up Windows Stuff™