* Cache users by objectID, and clear cache when updated via master key
* Go back to caching by session token. Clear out cache by querying _Session when user is modified with Master Key (ew, hopefully that can be improved later)
* Fix issue with user updates from different sessions causing stale reads
* Tests aren't transpiled...
* Still not transpiled
Session tokens generated by Parse with with "Expire inactive session" set
to No leave the the expiresAt field undefined. This fixes the TypeError
"Cannot read property 'iso' of undefined'" exception thrown when trying
to use a session token with undefined expiresAt.
