Print version info at start

Print version info at start

When debugging problems from logs, it would be useful to know what
version is running across program start and stop.  In one case I have
a suspicion that an upgrade was run inbetween but the logs don't help
identify that.

My first thought was to grab this from argparse just as --version
does, but that's not really currently possible [1].

The original starting message is probably irrelevant, but I realise
log messages tend to suffer from Hotel California syndrome; you can
check-in but you can never leave.

[1] http://bugs.python.org/issue9399

Change-Id: Ia1bfd2f3589b508e19fd8a94d59beaafd6d657d2