chore(package): update mongoose to version 4.8.4
chore(package): update mongoose to version 4.8.4

https://greenkeeper.io/
andrewlinfoot/keystone,benkroeger/keystone,andrewlinfoot/keystone,concoursbyappointment/keystoneRedux,andrewlinfoot/keystone,vokal/keystone,naustudio/keystone,vokal/keystone,Pop-Code/keystone,ratecity/keystone,matthewstyers/keystone,concoursbyappointment/keystoneRedux,benkroeger/keystone,matthewstyers/keystone,trentmillar/keystone,ratecity/keystone,danielmahon/keystone,danielmahon/keystone,benkroeger/keystone,trentmillar/keystone,trentmillar/keystone,frontyard/keystone,naustudio/keystone,danielmahon/keystone,frontyard/keystone,Pop-Code/keystone,vokal/keystone,matthewstyers/keystone,naustudio/keystone,frontyard/keystone