[Openid-specs-ab] Issue #1363: SIOP error response (openid/connect)

[Kristina Yasuda]

New issue 1363: SIOP error response
https://bitbucket.org/openid/connect/issues/1363/siop-error-response

Kristina Yasuda:

SIOP currently only defines “Relying Party Registration Metadata Error Response”. There has been a question, how SIOP can send an error response for any other reason. Suggest we introduce a more general error response section. 

SIOP error response in cross-device SIOP should also be defined. In same device SIOP, error response will be an HTTP 302 as defined in OpenID.Core.