[fix] relation thumb
[fix] relation thumb

1. destroy_thumbs method is public
2. don't file.set() when name not change

shirasagi/ss-handson,togusafish/shirasagi-_-shirasagi,shirasagi/shirasagi,sunny4381/opendata,hotmix/shirasagi,kaosf/shirasagi,shirasagi/shirasagi,itowtips/shirasagi,kaosf/shirasagi,shirasagi/opendata,mizoki/shirasagi,itowtips/shirasagi,bee01/shirasagi,tecyama/opendata,toyodundy/shirasagi,sunny4381/opendata,ShinjiTanimoto/shirasagi,t-wata-cldt/shirasagi,koba5884/shirasagi,koba5884/shirasagi,sunny4381/shirasagi,shirasagi/shirasagi,tany/ss,itowtips/ss-handson,bee01/shirasagi,hotmix/shirasagi,t-wata-cldt/shirasagi,togusafish/shirasagi-_-shirasagi,shirasagi/shirasagi,hotmix/shirasagi,toyodundy/shirasagi,kaosf/shirasagi,MasakiInaya/shirasagi,shirasagi/ss-handson,tany/ss,sunny4381/shirasagi,ShinjiTanimoto/shirasagi,koba5884/shirasagi,itowtips/ss-handson,t-wata-cldt/shirasagi,MasakiInaya/shirasagi,tany/ss,togusafish/shirasagi-_-shirasagi,MasakiInaya/shirasagi,bee01/shirasagi,toyodundy/shirasagi,kaosf/shirasagi,shirasagi/opendata,tecyama/opendata,masakiooba/shirasagi-1,ShinjiTanimoto/shirasagi,shirasagi/ss-handson,sunny4381/opendata,ShinjiTanimoto/shirasagi,itowtips/shirasagi,sunny4381/opendata,shirasagi/opendata,tecyama/opendata,tecyama/opendata,sunny4381/ss-handson,itowtips/ss-handson,t-wata-cldt/shirasagi,sunny4381/ss-handson,hotmix/shirasagi,togusafish/shirasagi-_-shirasagi,shirasagi/ss-handson,mizoki/shirasagi,itowtips/ss-handson,masakiooba/shirasagi-1,itowtips/shirasagi,masakiooba/shirasagi-1,sunny4381/shirasagi,shirasagi/opendata,sunny4381/ss-handson,mizoki/shirasagi,mizoki/shirasagi,MasakiInaya/shirasagi,koba5884/shirasagi,tany/ss,masakiooba/shirasagi-1,bee01/shirasagi,toyodundy/shirasagi,sunny4381/shirasagi,sunny4381/ss-handson