Added abstract to pod and various other changes

Hi,

I updated your dist to follow various conventions, which will make it work better with various tools and services:

* Added an abstract to the pod. You already have the abstract in a comment, so you could choose to use PodWeaver instead, I guess
* Reformatted Changes according to CPAN::Changes::Spec (will display more nicely in MetaCPAN, for example)
* Added github repo to metadata. Will appear in sidebar in MetaCPAN, and let other tools find / process it automatically
* Specified min perl version

Cheers,
Neil