Better settings interface

I found the admin/settings/signup_pay interface a bit clunky so I moved things around and changed some of the wording a little.

I put both of the receipt templates into their own collapsible field sets, so the page feels less cluttered and I think that this a pretty common way of handling these types of fields amongst other modules.

The "Role Weight" setting still needs some help though. I think the way it is worded would be challenging for a lot of users, but couldn't come up with anything better at the moment. Suggestions?