Show section status if available, and only show seat information if available

[Bad-Science]

As per #398 a new field status will be available on sections. We want to display this if it is available (if it is not null), either alongside or in place of the seats and seats_taken fields.

Additionally, if either seats or seats_taken are null, that information should not be displayed, and only the status should be displayed.

If status, seats, and seats_taken are all null, then neither of them should be displayed.

Before implementing this (or during), please post a screenshot or mockup of what it will look like in all four cases.

This issue will require editing the section template, and possibly the section controller.

This issue was migrated from YACS-RCOS/yacs-web#48