Use Information Content

[cbizon]

There are numerous results for things like "Procedure" or other high level terms from ontologies. We really don't like them, but others in the consortium want to keep them in. (See ranking-agent/aragorn#83 for an example). If we keep them, then we want to drastically downweight those answers IMO. One way to do this will be to look at the information content of nodes and use it somehow. NN returns IC values, but it's worth noting that we don't have IC for everything, just for terms from certain ontologies.