Add V3 API samples for ext-status,hypervisor,admin-actions

Partially implements blueprint v3-api-unittests

Change-Id: I537366c1824792fb5345544fc27647816d4d824f
Adds ext-status,hypervisors,admin-actions metafiles for api samples

Converts extended-status, hypervisors, admin-actions api sample to
create meta files for api sample docs.
We use this to auto generate the specification document

Change-Id: I825a6c623e7982b544fd4b616e17ab5335403bd8