Reinstated missing min_amount, max_amount config settings to xml.
Removed reference to percentage invoice fee from invoice payment method
Ported fix to part payment payment plan.
Hosted payment types have no associated cost, getCosts return 0 for these.
added back required config fields to xml for all payment methods
added preliminary documentation for payment method config settings to readme file
Merge branch 'feature/WEB-315_Fix_for_getCosts_looking_for_percentage_invoice_fee' into develop
merge