Cache users by objectID, and clear cache when updated via master key (fixes #1836) (#1844)

* 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

src/Adapters/Cache/InMemoryCache.js

@@ -53,7 +53,6 @@ export class InMemoryCache {
     if (record.timeout) {
       clearTimeout(record.timeout);
     }
-
     delete this.cache[key];
   }