Updates README with contributors
Updates README with contributors-header fix
Merge pull request #12 from john-h86/update-readme

Updates README with contributors. Thanks, John!
Add /rankings, /submissions, /teams
Add solution checker (/check)
Add authentication for admins (Devise)
Add a local mirror of Project Euler problems
Fix links to use plural /problems
Remove separate /check route
Add sign in/out to footer
Tidy up views; use strong parameters for teams
Use postgres in production
Remove redundant links on submissions/edit view
Add animated GIFs
Include correct attribution for Project Euler (CC BY-NC-SA 2.0 UK)
Remove example teams from production seeds
Delete non-templated problems/index.html
Merge restrict-signup
Create page for 5k event
Use Bootstrap for Rankings