Registration 3.1 - Elements names of lists should be plural

[Michael Jones]

The names of elements that are lists should be plural. Therefore, I propose that we change these names:

contact -> contacts redirect_uri -> redirect_uris js_origin_uri -> origin_uris (the JavaScript reference is confusing and probably unnecessary)

[Michael Jones]

Fix #373 Registration 3.1 - Elements names of lists should be plural

→ 7ea1cba4a643