Started on recurring payments.
Set billingfrequency to Day to test recurring payments.
Added debug code to Recurring payment.
Refactored the code.

Moved the Payment Type constants to IPN class.
Fixed a typo in IPN Controller.
Aligned the payment type constants.
Added type (once, recurring) to payment package.
Added Abstract_View_Payment.

Added breadcrumb to Package and Packages.
Added title to Package and Packages.
Added checks to ensure you use the correct gateway for payments.
Moved package view checkout link to view class.
Moved description to shared field.
Refactored the PayPalGateway into its own files.
Moved array_to_string from Controller_Payment_IPN to IPN class.
Recurring payments now create a payment transaction.
Merge branch 'feature/recurring-payment' into develop