add event_participants_path link
add event participants list view
add joined field to event_participants table
participant can check in event now
participants#index view used new layout now
sort by user.login as participant list
add photo uploader test. #228
add test code
Merge pull request #239 from saberma/saberma-enhancement/228-add-photo-uploader-test

增加缩小图片处理的测试
used new search method because this wouldn't run sql in loop
add new test code
merge.
reuse login_user.
when user is not the event creator, he can not allow to get check in event. #240
fixed rspec error.
show check in link. #240
Merge branch 'master' of github.com:saberma/19wu