Refactor to async TimescaleDB backend & add Alembic migrations

alembic.ini

@@ -0,0 +1,38 @@
+[alembic]
+# path to migration scripts
+script_location = alembic
+# default database URL; overridden by DATABASE_URL env var in env.py
+sqlalchemy.url = postgresql://postgres:password@localhost:5432/dereth
+
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARN
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARN
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+level = NOTSET
+args = (sys.stderr,)
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s