support system-wide global config

[FWDekker]

support a global config in /etc/mommy/mommy.conf or whatever (i should look up the specific paths and all) that provides a basis even before the user's own config is loaded. no need to install or package that global config, but allow specifying and loading from that path if it exists. the load order is then global>local>environment>command-line (i think)~