Verify the response status of create delete Image

This patch adds the JSON Schema for response status of Nova V2 Image
create, delete delete meta APIs and validate the response status with
added JSON Schema to block the backward incompatibility change in the
future.

create image, delete image & delete image meta does not return the
response body. Response status of above APIs is below-
create image - 202
delete image - 204
delete image meta - 204

Partially implements blueprint nova-api-attribute-test

Change-Id: Ia4864b3b7145a69dc257aba7f7612745b1b8254f
Merge "Verify the response status of create delete Image"