= Support for multiple instances of a social broker in a realm

It is now possible to have multiple instances of the same social broker in a realm.

Most of the time a realm does not need multiple instances of the same social broker. But due to the introduction
of the `organization` feature, it should be possible to link different instances of the same social broker
to different organizations.

When creating a social broker, you should now provide an `Alias` and optionally a `Display name` just like any other
broker.