fabric:container-create-ssh should check availibility of reqiured commands first

fabric:container-create-ssh should check availibility of reqiured commands first. When you are creating container on remote host which does not have all required commands used in installation scprit - it will fail on first missing command in the middle of the execution. After installation of missing command and waiting for another script execution you will find out another missing command. It would be cool if script could check availability of all required commands before triggering other time-consuming actions. Or at least list mandatory commands in help.