Pairing button can be clicked again after pairs are made

[kapil1garg]

Pairing button on the pairing page does not get disabled once pairs are made, which if clicked again will generate a new set of pairs. This has happened when people can't see the bottom of the page where pairings are displayed and assume pairings haven't been made, causing confusion when people refer to the pairings list at a later time and see they have different partners than when they first matched

In general, I think it would be good to provide a warning about making pairs that overwrite the existing ones and show whether pairings have been made or not closer to the top of the interface (or when the button is clicked as an alert).

Some cases to consider after pairings have been made the first time:

1. New people join the pool --> suggest making pairs again since new person is there
2. No new people in the pool, but new ratings are entered --> suggest making new pairs since there's more rating info now (but also inform user that this will overwrite current pairs)
3. No new people in the pool, and no new ratings --> provide warning that this will overwrite current pairings and have people confirm, OR make button unclickable so users have to click undo pairings and then make pairs