[etwist] clear ui cache at server startup time. Closes #1806933 this avoid pb when cubicweb/cubes provide new version of some js/css and also accumulating junk in the cache directories

#! /bin/sh -e
#

if [ "$1" = remove -o "$1" = upgrade ]; then
  if which install-docs >/dev/null 2>&1; then
    install-docs -r cubicweb-doc
  fi
fi

#DEBHELPER#

exit 0