Removed auth creds from paste files

The paste files do not need auth creds.  Only required in the
[keystone_authtoken] section of the api and registry configs.

See:
https://github.com/stackforge/cookbook-openstack-image/blob/master/templates/default/glance-api-paste.ini.erb
https://github.com/stackforge/cookbook-openstack-image/blob/master/templates/default/glance-registry-paste.ini.erb