Update KAPC Challenge Homepage

Recently, Polar created a new and updated KAPC Challenge Homepage that could potentially become the new Offical Homepage. I feel that it is time for a new Homepage, and this one should be approved and replace the current one. This new homepage has a new and updated nav bar, has many bugs fixed, a Winston Leaderboard page, a return to contests button, and runs the same way the old one did, only better.

Here's Polar's Comment on the Page:

Dear Mr. Lewis,

I have composed a potential update to the Contests homepage, which I would really appreciate if you took a look and let me know what you think. You can, of course change the design as you wish.

https://www.khanacademy.org/computer-programming/i/5670221057671168

This version uses the same data that you are using right now, so nothing would be different about the way you input data.

Sincerely,
Polar