Added Bootstrap 3 and made layout changes

!!! You might want to merge this before you make any more changes to the calendar (or anything else, really)

- Formatted the Main page, Log in, Sign up, Forgot password pages
- Removed gem 'rb-inotify' because it is Linux-only :)
- Switched to Bootstrap 3.+
- Cleaned up some of the CSS
- Cleaned up the application.html.erb file