Setup MaMMoS Gitlab

[samjrholt]

Initially, we could have a cron-job that pulls for each repo under the mammos project on Github and pushes this to a corresponding mirror organisation on Gitlab.mpcdf.mpg.de (or gitlab.gwdg.de if that is better for some reason). [More elegant would be an automatic scanning of repositories via the github API but that's probably over the top and not worth the effort.]