When passing a value via the FOODSOFT_DB_PREFIX environment variable the
FOODSOFT_FOODCOOPS environment variable will be overwritten with a list
of databases starting with the given prefix.
This can be used to dynamically generate the app_config.yml in a multicoop
installation and avoid listing all instances manually.
If the file app_config.defaults.yml exists in the working directory,
the content will be written to the config/app_config.yml and appended
by a configuration entry for every foodcoop in the space separated
environment variable FOODSOFT_FOODCOOPS.
