Discovery should be mandated for clients

[Joseph Heenan]

As noted in https://bitbucket.org/openid/fapi/issues/525/decide-on-what-to-do-for-a-cuckoo-s-token#comment-63894845 the current FAPI2 profile requires OPs to support discovery but does not mandate RPs to use discovery.

I believe this was an accidental omission and we should mandate RPs use discovery.

[Joseph Heenan]

PR created: https://bitbucket.org/openid/fapi/pull-requests/363/fapi2sp-add-requirement-for-rp-to-use

[Dave Tonge]

PR merged