Fix envs for store path

[joepio]

• ATOMIC_STORE_DIR sets the data-dir, and is not in the default.env. It should probably be renamed to ATOMIC_DATA_DIR
• ATOMIC_STORE_PATH sets the dir for the database. It's used in the docker.
• Make naming consistent (we use data-dir and store-path and store-dir. Some have subtle differences, but let's clear things up!)