The agent needs to be able to understand
if the agent token is supported and is a
mandatory feature of the ironic deployment
as that can alter some of the behavior of
the agent itself.
Also adds documentation on the subject for
administrators.
Story: 2007025
Task: 37821
Change-Id: Ic635e0ed6d378d6a34a4a82e66ca647eee33bc26
deca07de3c