On ubuntu 14.04, which uses upstart, where as our debian package uses
sysvinit, there is no stdout/stderr message printed when starting up,
because the start-stop-daemon swallows it.
As Elasticsearch is started to daemonize, we can remove the background
flag from the start-stop-daemon and thus see, if the system does not have
enough memory for starting up - something that happens often on VMs, since
Elasticsearch 5.0 uses 2gb by default instead of one.
Relates #21300
Relates #12716