discover.register(contact) API forces breaking encapsulation

[tristanls]

Requiring contact.transport when registering a contact (as shown below) violates encapsulation when Discover is used by another library. The below excerpt from tristanls/tart-ansible/index.js#L59 illustrates the problem:

    var registerDomain = function registerDomain(domainName, receptionist) {
        var data = {};
        Object.keys(transports).forEach(function (scheme) {
            data[scheme] = transports[scheme].data;
        });
        var contact = {
            id: domainName,
            data: data,
            transport: {
                host: discover.transport.host, // <- reaching all up in discover's pockets
                port: discover.transport.port
            }
        };
        domains[domainName] = receptionist;
        discover.register(contact);
    };

[tristanls]

In order to fix this, we need contact.transport to be optional (or preferably even disallowed) when calling discover.register(contact).

[tristanls]

Implementation of tcpTransport.setTransportInfo(contact) now enables Discover to add correct transport data to contact's upon registration.

[tristanls]

Resolved as of afe5f84