This patch is based on [1] and adds following scenarios:
GnocchiResourceType.list_resource_type
GnocchiResourceType.create_resource_type
GnocchiResourceType.create_delete_resource_type
[1] https://review.openstack.org/#/c/453861/
Change-Id: I54d9706ecf466ff28e2c18862c61a0f64b95cae5
Signed-off-by: Juha Kosonen <juha.kosonen@nokia.com>