Add a new line to the end of /etc/hostname.

To make printing the diff and generating diffs nicer, add
a newline to the end of the /etc/hostname file.
Add support for setting the IPv6 hostname.

Add an extra tasks to fix the IPv6 loopback address names, to match
the IPv4 names.  Also, mantain the original extra names attached as
well.
Merge pull request #6 from MJDSys/master

IPv6 support + a small fix