Use correct capability to check ability to export records

See issue #2534

Users with export_shop_reports capability should be able to export the shop reports. By validating against manage_options the code was denying users with the role shop_manager or shop_accountant (who have export_shop_reports capability but don't have manage_options) and limiting export to administrators only.
Merge pull request #2535 from jonjennings/patch-2

Use correct capability to check ability to export records