Use ec2-api-s3 instead of removed nova-objectstore
Use ec2-api-s3 instead of removed nova-objectstore

nova-objectstore was removed upstream and moved to an extra project
called ec2-api. Use the package and service from openstack-ec2-api now.

toabctl/openstack-quickstart,SUSE-Cloud/openstack-quickstart,sjamgade/openstack-quickstart