Prepare node exporters for textfile collection
    
    In order to facilitate collection of metrics for applications which
    do not expose any natively, as well as to replace legacy nsca based
    monitoring hooks, minions are prepared for textfile collection using
    the already installed Prometheus Node Exporter.
    For this, we deploy a canonical directory which textfile metrics can
    be placed in, and install moreutils to have `sponge` available for
    writing them.
    Given the low overhead this is deployed to all minions.
    
    Signed-off-by: Georg Pfuetzenreuter <mail@georg-pfuetzenreuter.net>