fix bundle install failure on travis-ci
fix bundle install failure on travis-ci

sunny4381/shirasagi,kaosf/shirasagi,ShinjiTanimoto/shirasagi,koba5884/shirasagi,sunny4381/shirasagi,tany/om,MasakiInaya/shirasagi,mizoki/shirasagi,toyodundy/shirasagi,sunny4381/opendata,sunny4381/shirasagi,sunny4381/ss-handson,tany/ss,sert-uw/shirasagi,tany/ss,sunny4381/ss-handson,tecoda/opendata,itowtips/shirasagi,tany/om,shirasagi/shirasagi,masakiooba/shirasagi-1,shirasagi/shirasagi,tecoda/opendata,mizoki/shirasagi,t-wata-cldt/shirasagi,kaosf/shirasagi,shakkun/ss-temp,ShinjiTanimoto/shirasagi,bee01/shirasagi,shirasagi/ss-handson,kaosf/shirasagi,mizoki/shirasagi,tany/om,MasakiInaya/shirasagi,shirasagi/ss-handson,gouf/shirasagi,hotmix/shirasagi,sert-uw/shirasagi,tecyama/opendata,sunny4381/shirasagi,bee01/shirasagi,sunny4381/opendata,koba5884/shirasagi,itowtips/ss-handson,togusafish/shirasagi-_-shirasagi,mizoki/shirasagi,shirasagi/ss-handson,tachikomapocket/shirasagi-_-shirasagi,tany/ss,gouf/shirasagi,MasakiInaya/shirasagi,sunny4381/ss-handson,t-wata-cldt/shirasagi,shakkun/ss-temp,bee01/shirasagi,tachikomapocket/shirasagi-_-shirasagi,sert-uw/shirasagi,sert-uw/shirasagi,tany/om,hotmix/shirasagi,sunny4381/ss-handson,ShinjiTanimoto/shirasagi,shirasagi/opendata,koba5884/shirasagi,bee01/shirasagi,koba5884/shirasagi,itowtips/shirasagi,t-wata-cldt/shirasagi,tachikomapocket/shirasagi-_-shirasagi,gouf/shirasagi,kaosf/shirasagi,hotmix/shirasagi,shirasagi/shirasagi,shirasagi/opendata,t-wata-cldt/shirasagi,togusafish/shirasagi-_-shirasagi,shirasagi/opendata,togusafish/shirasagi-_-shirasagi,gouf/shirasagi,toyodundy/shirasagi,shakkun/ss-temp,sunny4381/opendata,toyodundy/shirasagi,masakiooba/shirasagi-1,MasakiInaya/shirasagi,tecoda/opendata,tachikomapocket/shirasagi-_-shirasagi,toyodundy/shirasagi,tecyama/opendata,tany/ss,shirasagi/ss-handson,itowtips/ss-handson,tecyama/opendata,togusafish/shirasagi-_-shirasagi,hotmix/shirasagi,itowtips/shirasagi,masakiooba/shirasagi-1,tecoda/opendata,shirasagi/opendata,shirasagi/shirasagi,tecyama/opendata,sunny4381/opendata,masakiooba/shirasagi-1,itowtips/ss-handson,itowtips/ss-handson,ShinjiTanimoto/shirasagi,itowtips/shirasagi,shakkun/ss-temp