Add logging, add credit card and payment support. Add many more methods and clean up/comment some services.
Merge branch 'master' of https://github.com/hross/Spreedly.Net

Conflicts:
	src/Spreedly.Net/Model/AsyncClient.cs
	src/Spreedly.Net/Model/IAsyncClient.cs
	src/Spreedly.Net/Service/SpreedlyService.cs
	src/Spreedly.Net/Spreedly.Net.csproj
	src/Spreedly.Net/Spreedly/Transaction.cs