Added configuration updates for services.cfg and commands.cfg

Updated gluster_nagios spec file to update services.cfg
commands.cfg and nagios.cfg file.

The services.cfg file will have a common configuration for
all the nodes with a host group called "gluster_hosts".
One has to just add the list of host under this host group.

Signed-off-by: Timothy Asir <tim.gluster@gmail.com>