Add a Github Service Hook for Packagist

[cognifloyd]

I just submitted php-peg to packagagist (and added hafriedlander as a maintainer):
https://packagist.org/packages/hafriedlander/php-peg

From the Packagist website:

Enabling the Packagist service hook ensures that your package will always be updated instantly when you push to GitHub. To do so you can go to your GitHub repository, click the "Settings" button, then "Service Hooks". Pick "Packagist" in the list, and add your API token (see above), plus your Packagist username if it is not the same as on GitHub. Check the "Active" box and submit the form.

Grab the API Token from:
https://packagist.org/profile/