Issue #547: Add support for recording lab findings and chemicals detected.

The ChEBI ontology now has an API identical to the API of HPO.

Optimal batching size is 3000 for ChEBI. Takes 15 min to index.
Fixed some issues with the SolrUpdateGenerator.
This is painful... Don't reindex the whole ontology, this will bomb the EBI server with useless requests, especially since you're doing the reindex three times in a row. Plus, tests are executed in parallel, you're messing up with the index big time. You should mock the ontology as well, instead of downloading the whole thing from a remote host, either use a `file:///...` url, or mock the download part.