* Implemented tax collection for subscriptions
* Cleanup for Sales Tax
* Cleanup for Sales Tax
* Changes a constraint to an index for checking purposes
* Added and implemented a ReadById method for TaxRate
* Code review fixes for Tax Rate implementation
* Code review fixes for Tax Rate implementation
* Made the SalesTax migration script rerunnable
* Expanded the Plan model to make plan & product data a bit more dynamic
* Created a Product enum to track versioned instances of the same plan
* Created and API call and Response model for getting plan & product data from the server