Allow packages to disable immediate restart on package upgrade

Both package types, RPM and deb now contain an option to not restart on upgrade.

This option can be configure in /etc/default/elasticsearch for dpkg based systems
and /etc/sysconfig/elasticsearch for rpm based systems. If the RESTART_ON_UPGRADE option is set to false, the node will not be restarted after the package has been installed.

By default the setting is as before, where a restart is executed on upgrade.