ROBOT relax

[caufieldjh]

Describe the desired behavior

This has essentially been mentioned in #21 and #29 - to reduce some OBOs axioms to a more consistent relation type, we will need to run ROBOT relax as something like the following:
robot relax --input cteno.owl --output cteno_relaxed.owl

We can run ROBOT through Py4j, doing the actual relax right around here:

kg-obo/kg_obo/transform.py

Line 393 in 7dab134

This should render most OBOs more graph-compatible in general.

[caufieldjh]

As part of this functionality, should diff the input and output to verify that:

• Something actually happened
• Ontology structure has changed