Added Changes file and ensured github repo is included in metadata

Hi,

I've added a skeleton Changes file that conforms to CPAN::Changes::Spec. I put in all the releases you've done, getting the dates from [BackPAN](http://backpan.perl.org/authors/id/I/IA/IANKENT/), and then changes from the git log.

I also added the github repo to Makefile.PL, so it will appear in the dist's metadata. This means it will be listed on the sidebar in MetaCPAN, for example. I also specified the bugtracker, setting it to be RT, otherwise it would switch to being github issues

Cheers,
Neil