Initialization bug fix for match_data.json

Previously, client requests for match data would return 404 because
the backing file is not present until the admin updates the match
status.
Front-end style tweaks

- Removed default Bootstrap style from layout
- Added a new app.css file & changed layout to use it
- Removed in-line styles from main_page template
- Misc. style tweaks across site
Re-added thin to Gemfile