uc_migs 6.x-1.2

Resolves the following issues:

* #568338: Able to bypass validation on payment amount
* #664284: Cancelling an order / order erroring out returns the user to a page with no menus.
* #826574: Add theme functions for provider logo display
* #826526: Add theme function for failed order page

* Add tokens for MIGS receipt (stored in order data). Display of the receipt number is a requirement for some banks.
* Exit earlier if secure secret is not configured.
* Improvements to output templates.

Fixes SA-CONTRIB-2010-064 - Ubercart MIGS Payment Gateway - Web Parameter Tampering.