Make the number of processing attempts admin configurable.
Refactored to a retry status system.

Not happy with how the attempt counter works. Needs additonal work because log messages
are not accurate.
Refactor sustainer processing to use a retry status.
Add implementation of new fundraiser_sustainers_donation_fail hook.
Add test for retry system. Refactor sustainer key creation.
Merge branch '7.x-4.x' into 7.x-4.5.1-beta1_configurable_sustainer_attempts
Add attempts column to recurring donation lists.

Also made the list of recurring donations more consistent
between view and edit.
Merge branch '7.x-4.5.1-beta1_configurable_sustainer_attempts' into 7.x-4.x