Store should remember the ontology path it was created with

Imagine I do the following:

tracker endpoint --database=/tmp/my-database --ontology-path=/tmp/my-custom-ontology
tracker sparql --database=/tmp/my-database ...

Q. What ontologies will the tracker sparql command use? A. The Nepomuk ontologies.

This is counter intuitive, if I create a store with a custom ontology then I probably want to always use that custom ontology.

This issue is noticable in the CI failures for !198 (merged) and !200 (merged). These tests are creating a database using an uninstalled copy of the Nepomuk ontologies, and then running CLI commands which fail as they try to use ontologies from $prefix which are not present.

I guess we should fix this by storing the ontology path with the database somehow, perhaps a minimal config file would make sense ? The other option would be to add the --ontology-path argument to every single command, which seems less convenient.