Ensure JSON headers in Auth Requests

The Content-Type header will be set automatically by the request call
however we should also ensure that we set the Accept header because our
auth plugins only work with JSON.

Change-Id: Ib3badd70f4fa32d400565c39a072db547d86037e
Updated from global requirements

Change-Id: Icc5f3cdf0cfe9a1566ff5efafc85471381e3622d
Merge "Ensure JSON headers in Auth Requests"
Merge "Updated from global requirements"