add event order participant model.
send sms to user after participant record create.
update settings.yml.example
send checkin code to user after paid.
hide user checkin button.
fixed checkin index page error.
remove old participant model.
fixed event change error.
remove checkin and join business.
remove checkin and join files.
add migration from event participant to order participant.
fixed migration error.
use let! instead of let.
merge master.
don't send email when migrate data.
merge master.
fixed rspec error.
fixed rspec error.
merge master.
fixed rspec error, add stub_alert and stub_confirm rspec support methods.