fix Object.keys usage
fix Object.keys usage

nolanlawson/pouchdb-find,nolanlawson/pouchdb-find,wehriam/pouchdb-find,wehriam/pouchdb-find,nolanlawson/pouchdb-find,wehriam/pouchdb-find,nolanlawson/pouchdb-find,wehriam/pouchdb-find