move payment gateway settings inline, removing the settings sidebar.
render list of payment gateways more similar to the wordpress plugins page.
improve handling of display names for payment gateways
add current display name to payment gateway table. improve cancel button on payment gateway settings rows.
improve layout of settings form and buttons in payment gateways table
Merge pull request #329 from InstinctBrett/improve-payments-admin-page

Improve payments admin page (issue #325)