CSIV2 — No Tokens in EstablishContext Message

The spec doesn't say whether or not an EstablishContext with none
of cleint authentication, identity, or authorization token is
legitimate.

I don't think we need the ability to send such mecahnisms (for
unprotected requests), as we would just send the request without a CSIv2
service context element. The only down side I can see, to writing this
empt EstbalishContext out of spec, would be that a client could not use
it to get feedback from a TSS in the form of CompleteEstablishContext,
indicating that the TSS supports CSIv2.

We must indicate that this is either an invalid msg, or state that it
must be supported (and what it's semantics should be).

close issue with no change