snackpot.yml etc. - refine docker-compose config deploy

The main job of this commit:
- Be explicit about templates: expect the .j2 extension
- Copy all other files, so that they can be binary
- Don't deploy dotfiles or dotdirectories.

This snuck in:
- Remove `test` tag
- Refine some descriptions

templates/docker-compose/postgres/init.sql.j2

@@ -0,0 +1,6 @@
+CREATE USER {{ nextcloud_db_user }};
+ALTER USER {{ nextcloud_db_user }} WITH ENCRYPTED PASSWORD 'md5{{ (nextcloud_db_password + nextcloud_db_user) | hash("md5") }}';
+DROP DATABASE IF EXISTS {{ nextcloud_db }};
+CREATE DATABASE {{ nextcloud_db }} TEMPLATE template0 ENCODING 'UNICODE';
+ALTER DATABASE {{ nextcloud_db }} OWNER TO {{ nextcloud_db_user }};
+GRANT ALL PRIVILEGES ON DATABASE {{ nextcloud_db }} TO {{ nextcloud_db_user }};