Use unicorn_rails as web server in production

- Change procfile
- Remove thin
- Use 4 worker processes
- Use unicorn_rails instead of "unicorn"
Add newrelic to monitor the application in production and puts some gems in their right place.
Merge branch 'master' of github.com:catarse/catarse
Merge branch 'master' of github.com:catarse/catarse
Merge branch 'master' of github.com:catarse/catarse