Add error handling to leaderboard POST (new inductee)

[snphillips]

Nothing happens if user can't add a new inductee to the leaderboard. User just hammers away at submit button.
Come up with and implement a solution. This happens when Heroku is doing maintenance or when user tries to add name longer than 12 characters

To replicate:

• play game get a high score
• when presented with leaderboard, try to add name longer than 13 characters