[server] remove not-so-useful entity_name and entity_attr functions, introduce entity_oldnewvalue entity_oldnewvalue(entity, attr) is usable in before_update_entity and returns both old and new value of entity

#! /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