Add UID/GID option and custom config base for docker

Closes #13

docker/example-config.yaml

@@ -0,0 +1,66 @@
+# The full URI to the database. SQLite and Postgres are fully supported.
+# Other DBMSes supported by SQLAlchemy may or may not work.
+# Format examples:
+#   SQLite:   sqlite:///filename.db
+#   Postgres: postgres://username:password@hostname/dbname
+database: sqlite:////data/maubot.db
+
+plugin_directories:
+    # The directory where uploaded new plugins should be stored.
+    upload: /data/plugins
+    # The directories from which plugins should be loaded.
+    # Duplicate plugin IDs will be moved to the trash.
+    load:
+    - /data/plugins
+    # The directory where old plugin versions and conflicting plugins should be moved.
+    # Set to "delete" to delete files immediately.
+    trash: /data/trash
+    # The directory where plugin databases should be stored.
+    db: /data/plugins
+
+server:
+    # The IP and port to listen to.
+    hostname: 0.0.0.0
+    port: 29316
+    # The base management API path.
+    base_path: /_matrix/maubot/v1
+    # The base appservice API path. Use / for legacy appservice API and /_matrix/app/v1 for v1.
+    appservice_base_path: /_matrix/app/v1
+    # The shared secret to sign API access tokens.
+    # Set to "generate" to generate and save a new token at startup.
+    unshared_secret: generate
+
+# List of administrator users. Plaintext passwords will be bcrypted on startup. Set empty password
+# to prevent normal login. Root is a special user that can't have a password and will always exist.
+admins:
+    root: ""
+
+# Python logging configuration.
+#
+# See section 16.7.2 of the Python documentation for more info:
+# https://docs.python.org/3.6/library/logging.config.html#configuration-dictionary-schema
+logging:
+    version: 1
+    formatters:
+        precise:
+            format: "[%(asctime)s] [%(levelname)s@%(name)s] %(message)s"
+    handlers:
+        file:
+            class: logging.handlers.RotatingFileHandler
+            formatter: precise
+            filename: /var/log/maubot.log
+            maxBytes: 10485760
+            backupCount: 10
+        console:
+            class: logging.StreamHandler
+            formatter: precise
+    loggers:
+        maubot:
+            level: DEBUG
+        mautrix:
+            level: DEBUG
+        aiohttp:
+            level: INFO
+    root:
+        level: DEBUG
+        handlers: [file, console]