manipulate network service in %post (#1369794)

Due to #1369794 , anaconda cannot currently manipulate sysv
services in F25+. So to work around this, take 'network' out of
the services lines in all kickstarts and instead manipulate
it in the %post section, with chkconfig.

Also remove rsyslog from the Atomic image services line because
it doesn't appear to be included in the OStree tree at present
and so attempting to enable the service breaks Atomic image
compose, see e.g.:

https://kojipkgs.fedoraproject.org//work/tasks/9022/15349022/oz-x86_64.log

also correct the name of the ssh service in fedora-arm-base.ks;
it's sshd not ssh.

fedora-atomic.ks

@@ -21,8 +21,7 @@ firewall --disabled
 bootloader --timeout=1 --append="no_timer_check console=tty1 console=ttyS0,115200n8"
 
 network --bootproto=dhcp --device=link --activate --onboot=on
-services --disabled=network
-services --enabled=sshd,rsyslog,cloud-init,cloud-init-local,cloud-config,cloud-final
+services --enabled=sshd,cloud-init,cloud-init-local,cloud-config,cloud-final
 
 zerombr
 clearpart --all
@@ -125,5 +124,9 @@ echo "(Don't worry -- that out-of-space error was expected.)"
 echo "Adding Developer Mode GRUB2 menu item."
 /usr/libexec/atomic-devmode/bootentry add
 
+# Disable network service here, as doing it in the services line
+# fails due to RHBZ #1369794
+/sbin/chkconfig network off
+
 %end