update layout for signups

[markjjackson]

Ticket wingscms/wings#263: Different layout for signup campaign

Signup campaigns don't need the wall of text. That makes sense for petition campaigns, and signup campaigns simply inherited the layout, but it's a bad UI/UX for signup campaigns.

• The title/intro/text bit should be placed above the form on all viewports
• Title / intro / text should have text-align: center
• the 'read more' button should not be present. Just remove the collapse/expand mechanism altogether, it will never be used on signup campaigns. (If you want to show a wall of text before people sign up, that is what the petition setup is for)
• ideally, the form fields should be presented in two columns, if you can easily do that. If not, save that for a later improvement.

current problem

Most of the time, there is not enough text to place on the left

improvement:

it would save a lot of space if the fields would be in two columns, but at least this doesn't look so weird that you would make up nonsense copy just to fill up the gap.