Ironic has already implemented its own microversion mechanism, and
the header name is X-Ironic-API-Version, not X-Baremetal-API-Version.
Because Ida9f60d8cbd0dcf48669b82e619fc4016ee0bcb7 removed program
terminology from the governance repo.
The microversions of Nova is not used yet. And for consistency of
whole OpenStack projects, this patch changes microversion header
names on Nova side.
Partially implements blueprint api-microversions
Change-Id: I3ea2b2982c5f792c82832d772ae951b157da8b39
Depends-on: I1b43e2662107ad81e57b96f0c9430c61b795fdea
9a792e0f72