Run Initial Setup in reconfig mode on IoT images

Use the "firstboot --reconfig --enable" command[0] to tell
Initial Setup that it should run in the reconfig mode.

[0] http://pykickstart.readthedocs.io/en/latest/kickstart-docs.html#firstboot

fedora-iot.ks

@@ -15,6 +15,9 @@ bootloader --timeout=1 --append="console=tty1 console=ttyS0,115200n8 console=tty
 network --bootproto=dhcp --device=link --activate --onboot=on
 services --enabled=NetworkManager,sshd,rngd,initial-setup
 
+# tell Initial Setup to run in the reconfig mode
+firstboot --reconfig --enable
+
 zerombr
 clearpart --all
 autopart --nohome --noswap --type=plain