travis: go back to trusty; install new bundler
travis: go back to trusty; install new bundler

rbns/the-idb,dra/the-idb,dra/the-idb,rbns/the-idb,rbns/the-idb,idb-project/the-idb,dra/the-idb,idb-project/the-idb,rbns/the-idb,idb-project/the-idb,dra/the-idb,idb-project/the-idb