Adding the following:
1. Added a new attribute called package-instance-name to use it as label in the context bar.
2. Added a new proc called apm::package_version::attributes::set_all_instances_names which changes all instances names for those packages that have the attribute package-instance-name and the instance name is equal to package-name.
3. Added a new proc called apm::package_version::attributes::get_instance_name which gets the package-instance-name for a given package-key.