Caches should be cleared when deploying the webapp
When deploying the web application to production server, Varnish and Memcached caches should be cleared in order for the new version of swh-web to be immediately served to clients.
Currently, there is a delay of several minutes until previously cached pages get invalidated. This can result in a website badly displayed due to changes in static assets (especially css files) not taken into account.
Migrated from T1100 (view on Phabricator)