Added a new app generator for creating a working terra app right away.
Added a "SingleWorkflow" for easy workflow creation.
TERRA_SETTINGS_FILE can now be passed along to containers directly without relying on the compose file to do it for you. This should be backwards compatible with the compose file method.
~Remove the default compose files from the container services, so that inheriting can be simplified. This should be backwards compatible with the old inheritance pattern.~
TERRA_SETTINGS_FILEcan now be passed along to containers directly without relying on the compose file to do it for you. This should be backwards compatible with the compose file method.