Create a new API endpoint to retrieve just the list of packages related to an user

This new endpoint provides just the list of packages, without their ACLs
and should thus speed up query for someone's packages.

Relates to https://fedorahosted.org/packagedb-cli/ticket/20
List the new API endpoint in the API documentation
Add an error when none ACLs are found for the user
Add the default output status
Add commit ACL on geany/master to pingou
Adjust the unit-tests for pingou's new ACL on geany
Add unit-tests checking the new /api/packager/package endpoint