legacy: fix missing imports

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>
base: better signaling support for cli

* NOTE CFG_FLASK_SERVE_STATIC_FILES is set only for `runserver` command.
  Please add it to your local config if you want to enable it for your
  server.

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>