As extensions options has been deprecated, API sample tests
should run against all extension enable.
This commit enables all extensions for Image API tests and remove its specific
extensions tests and sample files.
Also adds some basic hack to merge all APIs tests for all extension.
Partially implements blueprint api-sample-tests-with-all-extensions
Change-Id: Ib603fbccfdc09b25d4c69c872d79e4cafc30fff5