Enhancing SDK design

BuddycloudAPIEndpoint is a Builder which composes an endpoint URL (e.g. "https://buddycloud.org:80/api"). Version field is ignored.

BuddycloudConfiguration, on the other hand, will encapsulate a JsonObject (ralfstx/minimal-json) with overrides to the default configuration properties (e.g BUDDYCLOUD_DOMAIN="buddycloud.org");