Code review comment for ~t0rrant/cloud-init:1819966-sysconfig-options

Ryan, thanks for the suggestions.

Using write_files module with append mode seems counter-intuitive, although is a reasonable workaround.

I will look into implementing that cc_sysconfig module. What is your thought on making cloudinit.net renderer to leave the `/etc/sysconfig/network` file as is, i.e: not writing the `NETWORKING=yes` at all, if the user does not specify anything with the sysconfig module? Would there be any downside to this?