Added TLS 1.2 and TLS 1.1 code as Spreedly are turning off TLS 1.0 and the current code didn't work with their testing endpoint provided
Added TLS 1.2 and TLS 1.1 code as Spreedly are turning off TLS 1.0 and the current code didn't work with their testing endpoint provided

philjones88/SpreedlyCoreSharp