livemedia-creator: pass inst.cmdline for headless installs (#985487)

Also add console=ttyS0 so you can run virsh console XX to follow the
install/look for errors.

src/sbin/livemedia-creator

@@ -281,6 +281,8 @@ class VirtualInstall( object ):
             args.append(disk_opts)
 
         extra_args = "ks=file:/{0}".format(os.path.basename(ks_paths[0]))
+        if not vnc:
+            extra_args += " inst.cmdline console=ttyS0"
         if kernel_args:
             extra_args += " "+kernel_args
         if iso.liveos: