Make the Bewit builder pipeline more Fluent-ish

[gmiserez]

Is your feature request related to a problem? Please describe.
The Bewit builder pipeline could be more Fluent-ish.

Describe the solution you'd like
Instead of this:

    public class BewitRegistrationBuilder
    {
        public Func<INonceRepository> GetRepository { get; set; }
    }
}

do this:

    public class BewitRegistrationBuilder
    {
        internal Func<INonceRepository> GetRepository { get; private set; }

        public BewitRegistrationBuilder SetRepository(Func<INonceRepository> create)
        {
            GetRepository = create;
            return this;
        }
}