Stripe .NET 1.12.0

This release of Stripe.NET contains the following changes:

• Adds support for fixed-dollar-value coupons
• Adds an overload of CancelCustomersSubscription taking a specific subscription ID (thanks @jtompkins)
• Renames mis-named methods, DeleteCard and ListCards (reported by @brpeanut)

Stripe .NET 1.12.0-beta1

Prepare for 1.12.0-beta1 release

Upgrades RestSharp to latest version

Stripe .NET 1.11.0

v1.11

added cards api and updated tokens api

Stripe .NET 1.10.0

• Add account_balance to update customer request.