Added github repo and license type to metadata and tweaked Changes format

Hi,

I've updated Makefile.PL so that the license type and github repo will be included in the metadata for your dist. This means MetaCPAN will be able to display this information, for example.

I've also tweaked the formatting of your Changes file to conform to CPAN::Changes::Spec. This means various tools can process your Changes file. For example MetaCPAN will be able to display the latest Changes along with your dist.

Cheers,
Neil