use custom images for relation icons
Merge pull request #108 from garyposter/rel-indicator

This simply hooks up relation icons per the design.  If you want to QA, turn on the feature flag (`http://localhost:8888/:flags:/relationCollections/`), make a relation, and verify that the green circle shows up.  The aggregatedStatus function is just a stub at this point, so it will only ever be green in this go-round.