Add support to store and show section status in place of seat numbers

[Bad-Science]

It seems as though we will be unable to acquire exact seat numbers for NYU, at least initially. Instead of providing seat numbers, NYU's system displays a status text instead.

The possible statuses of a section are:

`Open`
`Closed`
`Wait List (<N>)` (although all I have seen is `Wait List (0)`
`Cancelled`

YACS should be able to ingest a status as well as seat numbers, but not require either to function. If seat numbers are not available, they should not be displayed, and if a status is not available, one should not be displayed.

This actually works out well, because we have received feedback from students at RPI in the past that showing only the number of seats total and the number of seats available often leaves some confusion as to whether a section is closed. So we should add a status to the RPI data adapter based on the number of seats. Because the status can be derived in the case of RPI, this will technically be redundant, but it is a small amount of data and will improve clarity and generalization.

This issue can be marked completed when the following subtasks are completed:

• Show section status if available, and only show seat information if available #396 Modify frontend to show status if available, and seats if available
• Add status to sections #280 Add status to sections table & APIs
• Make seats and seats_taken optional, add status column #279 Make seats columns optional
• Add status field based on seat numbers to banner adapter #397 Add status field based on seat counts in banner adapter
• Logic to determine a closed section should be modified. #433 Logic to determine a closed section should be modified

This issue was migrated from YACS-RCOS/university#8