26 error handling

[mikeheft]

Adds middleware to catch all errors. This allows us to have a more consistent error shape for all error and reduces the need for special handing in each controller.

• New middleware in app/middleware/error_handling
• Dynamically creates custom error classes to map internal errors like PG errors and ActiveRecord errors into out shape. This ensures the shape for all errors is able to be mapped consistently for future development ease.