Messages - Create acr_values request parameter

[Michael Jones]

The working group had previously decided to make top-level parameters for max_age, ui_locales, and claims_locales. I assume we also want to do this for an acr_values parameter, and to change default_acr to default_acr_values in Registration, as previously discussed.

This is the last major piece of functionality that can only be accomplished by requesting individual claims (other than requesting the individual claims themselves).

[Michael Jones]

Fixed #765 - Created "acr_values" parameter and changed "default_acr" to "default_acr_values"

→ <<cset d331039d3290>>

[John Bradley]

We need to add security considerations for why signing acr maxage and other security related things in the request.

[Michael Jones]

Fixed #765 - Added Security Considerations about the need for signed and encrypted requests

→ <<cset 0fcdb5979d93>>