Load topicmap topics including childs (#653).

BREAKING CHANGE

The Topicmap API's `getTopicmap()` method has a 2nd parameter: `fetchComposite`. If true the topics contained in the topicmap will include their child topics.
{{{
TopicmapViewmodel getTopicmap(long topicmapId, boolean fetchComposite)
{{{

REST API:
{{{
GET /topicmap/{id}?fetch_composite={true|false}
}}}
The fetch_composite parameter is optional. Default is false.

See #653