script: binding address+port config variable

• NEW Adds SERVER_BIND_ADDRESS and SERVER_BIND_PORT to overwrite bind address and port independently from the public URL. This gives control over the used network interface as well as the ability to bind Invenio to a protected port and use a reverse proxy for access. Priority of the config is (1) runserver command arguments, (2) SERVER_BIND_ADDRESS and SERVER_BIND_PORT configuration, (3) data from CFG_SITE_URL, (4) defaults (127.0.0.1:80).

Signed-off-by: Marco Neumann <marco@crepererum.net>
Reviewed-by: Jiri Kuncar <jiri.kuncar@cern.ch>