Build in-site subscription widget

Problem/Motivation

Clients should be able to see how much time is left in their trial and subscribe to make the site permanent from within the site.

Proposed resolution

Create floating block to display the time remaining in the trial, expandable to show subscription purchase form.

Remaining tasks

1. Get API to retrieve site expiration time from DevPanel, or store the expiration time during site launch.
2. Write code for floating block or select module to provide it.
3. Create code for subscription purchase form.
4. Add widget to site on launch.