adds on-the-fly metadata recording
bump dynalite to 0.4.0
implement metadata tracking for cardboard.insert
implement metadata tracking for cardboard.del
test that delDataset removes metadata
add cardboard.getDatasetInfo
consolidate size/count updates to a single reqeust
pass tests after rebase with master
implement metadata tracking for update-case of cardboard.put
Merge pull request #52 from mapbox/metadata

Dataset metadata