[#1667] converted subscription status to an enumeration
[#1667] converted subscription status to an enumeration

ronin1/braintree_dotnet,scottmeyer/braintree_dotnet,ronin1/braintree_dotnet,scottmeyer/braintree_dotnet,ronin1/braintree_dotnet,braintree/braintree_dotnet,scottmeyer/braintree_dotnet,braintree/braintree_dotnet,scottmeyer/braintree_dotnet