Spatialmatch relevance sort refactor

Refactors spatialmatch relevance sort. Results in cleaner, more consistent order of best results at the end of spatialmatch.

- Removes weird exception for address indexes in sort order.
- Adds mutation of input sets to setrelevance such features not contributing to relevance score are set to false.
- Tightens conditions of `geocode-unit.test.js` -- we're passing a higher bar now

### TODO

This represents a pretty big change to carmen -- will bump up to 0.7.x.

- [x] Add test coverage for setrelevance mutation
- [x] Final review/test/merge

cc @ingalls @morganherlocker