Allow replacing bash by custom command passed as first argument to wrapdocker.
Allow replacing bash by custom command passed as first argument to wrapdocker.

This makes creating inherited containers a little more convenient, for instance a gocd agent container would be something like:

    FROM dind
    # commands to install undaemonized go-agent go here
    CMD ["wrapdocker", "/usr/share/go-agent/agent.sh"]

ContainerSolutions/dind,pugna0/dind,stevenzeiler/dind,lstephen/docker-docker,cviebig/docker-arch-docker,dit4c/dind-binary,taskcluster/dind-service,pombredanne/dind,fearenales/dind,tomdee/dind,sttts/mesos-dind,lindenlab/dind,azukiapp/dind,karlkfi/dind,taskcluster/dind-service,jpetazzo/dind,pekermert/dind,djmaze/dind,resin-io-projects/resin-aerofs,pcarranzav/resin-aerofs