specify default ordering semantics

datacat will merge in asciibetic order with the last-merged
overwriting/appending to the earlier merged

This establishes the hierarchy as:

    mcollective::server::setting (10)
    mcollective::client::setting (30)
    mcollective::user::setting (70)

But also sets defaults for user iteration as 60 so they're more easily
overriden by users.