Add foodcoop-adam fork

[wvengen]

After the main version of Foodsoft is up and running (first milestone), work can begin to prepare for Dutch foodcoops to join in. They currently use the foodcoop-adam fork of Foodsoft - a temporary measure until these features are integrated more cleanly in the main version (foodcoop-adam/foodsoft#163).

So in the meantime, the foodcoops.net infrastructure will run the foodcoop-adam fork. This needs to be Dockerized, and integrated in the docker-compose configuration.

Two versions will need to be run: one as is, and another with the vokomokum plugin enabled (this is a special integration for a large foodcoop that is slowly migrating to Foodsoft for ordering, half using Foodsoft and half using their own system). Maybe in the future this will remain needed, maybe not (depends on how Foodsoft progresses).

[wvengen]

I don't think this is a good idea anymore. Also, experience with the foodsoft-latest docker instance shows that it does use some memory. It's better to move foodcoop-adam users to upstream Foodsoft, when all features have been merged.