Added a definedness test, this is handy for redeploying. Actually, we ought to be more subtle than this, and use something that adds lines to a file, because that's more likely to be useful.
Fixed a few issues where commands needed to work from a clean environment
Don't use a template, use lineinfile. This is more integrated for ansible, and allows better updating, as an existing hosts file doesn't end up removing entries. Note that we currently replace by IP, not by name. This could be an issue, but not likely to be.
Fixed bad updates to /etc/hosts