Instead of using the '-f' parameter to start elasticsearch in the
foreground, this is now the default modus.
In order to start elasticsearch in the background, the '-d' parameter
can be used.
Closes#4392
In order to be sure that memory mapped lucene directories are working
one can configure the kernel about how many memory mapped areas
a process may have. This setting ensure for the debian and redhat initscripts
as well as the systemd startup, that this setting is set high enough.
Closes#4397