Handin history refreshes every 10 seconds. Fixes #33

Please ignore .gitignore, Gemfile, Gemfile.lock, and database.yml.template. I had trouble installing debugger2 so I had to make some changes to Gemfile. Also, I thought gitignore would ignore Gemfile, but it somehow still got added to the push. Sorry!

With that aside, I have added a script in _submission_history_table.html.erb that auto-refreshes the page every 10 seconds. This can easily be adjusted to other time intervals should this be inconvenient.

Thank you!