Add auto shard.host to config.ini if $HOST defined.

AWS does not provide a useful os.hostname() value. This hack addresses
this by sort of taking advantage of a different hack I have installed.
in my .bashrc file I have which is basically:

HOST=`/usr/bin/wget -q -O-
http://169.254.169.254/latest/meta-data/public-hostname`

also useful, would be either the internal or external IP address.
Basically, any way we can connect to the machine that actually handles
this.