FIX pin zone.js version because of https://github.com/pouchdb/pouchdb/issues/6603#issuecomment-315735868
FIX pin zone.js version because of https://github.com/pouchdb/pouchdb/issues/6603#issuecomment-315735868

pubkey/rxdb,pubkey/rxdb,pubkey/rxdb,pubkey/rxdb,pubkey/rxdb