Allow multiple schedules in the same container (#78)

* Allow mounting of config directory for multiple schedules

* Add docs for conf.d feature

* Fix behavior on multiple files

* Define default case first in entrypoint script

test/compose/docker-compose.yml

@@ -21,7 +21,7 @@ services:
     volumes:
       - webdav_backup_data:/var/lib/dav
 
-  backup: &default_backup_service
+  backup:
     image: offen/docker-volume-backup:${TEST_VERSION:-canary}
     hostname: hostnametoken
     depends_on: