Address the SQL Alchemy warning about overlapping relationships.

The SQLAlchemy error is basically saying that we could get into trouble if we had a transition that went from a state in one capability to a state in another capability. This is because the capability_name would be one thing for the from state and something else for the to state, but there’s only one column for the capability_name, so one of them would overwrite the other. This solution tells SQLAlchemy "our application won’t let that happen, so stop worrying so much SQLA"