Rafactor glance api to merge defaults
Rafactor glance api to merge defaults

This code cleanup simplifies one the tests by merging the
specified params over the defaults instead of returning either
the defaults or the specified params.

bodepd/puppet-glance,gwdg/puppet-glance,varunarya10/puppet-glance,bodepd/puppet-glance,TelekomCloud/puppet-glance,aquto/puppet-glance,aimonb/puppet-glance,varunarya10/puppet-glance,mjeanson/puppet-glance,aimonb/puppet-glance,aquto/puppet-glance,TelekomCloud/puppet-glance,gwdg/puppet-glance,mjeanson/puppet-glance