Anal-retentive alphabetical ordering
Add variables for the runtime kernel parameters
Bind SSH to all IPv4 addresses by default

There's no sane default here with varying network interface names.
Eliminate "changed" condition when registering cjdns_port

This task will still report failures properly, but the cjdns_port value
will not change on most playbook runs. The tasks that subsequently use
the registered variable will report as changed when appropriate, so this
just cleans up the ansible-playbook output.