free event can be check in.
change sms message.
add db:migrate schema.
Merge pull request #601 from saberma/saberma-feature/free-event-can-be-check-in

免费活动也会发送签到码短信
show user phone.
Merge pull request #605 from saberma/saberma-enhancement/show-user-phone

签到列表显示用户手机号码