Saving uid and apiToken to cloud storage.

Current saves just the uid and apitoken to the user cloud storage.

We can remove all references to local storage and replace with cloud storage as:

"When Chrome is offline, Chrome stores the data locally. The next time the browser is online, Chrome syncs the data. Even if a user disables syncing, storage.sync will still work. In this case, it will behave identically to storage.local." - from the documentation.

So we can just replace with synced storage with no issues for users that are not using it.

Tested, with no bugs. Submitted to test branch so that anything I've overlooked can be checked over before a total conversion.