LaunchApp.java: added JVM shutdown hook draft.
ConfigManager.java: preliminary serializable class that will be used to hold configurations
FileManager.java: Create necessary in case user stored credential do not exist.
User.java: move the part that stores credential into shutdown hook in persistance package.
ShutDown.java: this class extends the Thread class and will be called when JVM is about to shutdown to save all necessary configurations, sync progress (for resumable uploads), etc.