Next step in refactoring the code to make it more readable and understandable:
-Split the controller into several different controllers as suggested in a previous pull request comments: A different controller for each function of the backend. This way we can avoid a MegaClass in Backend controller
-Split the access to Google API functions from the class GoogleAccess to two different classes: DatastoreAccess and CloudStorageAccess
-Added some interfaces to make the project more manageable in the future, just in case we need to switch to another cloud service provider

Everything is tested and works fine