update the install docs for centos-7 and fix the passenger ruby command
update the install docs for centos-7 and fix the passenger ruby command

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