Merge branch 'develop' into v1.0
Update CHANGELOG.md
Added AllowPartiallyTrustedCallers assembly attribute
Updated Vault objects; Minor code refactoring
Updated samples
Update README.md
Update CHANGELOG.md
CreditCard.cvv2 type should be string (per guidance from API team)
Added static methods for every non-static method available in model objects
Removed PaymentCardToken class (no longer used)
Refactored/fixed some unit tests
Added sample for creating billing agreement with credit card
Merge branch 'v1.0' into develop