Update StoreConfiguration.store() to return a Generic Store.

Currently StoreConfiguration.store() returns a Store implementation that does not have a generic type. This means we have to cast to get the generic types working correctly. Upon doing some research all store types EXCEPT for memory store are generic. We will update memory store to be generic and refactor the config classes to return stores with the proper generic type.

See :

 store = (SQLStore<Message>) DataManager.config("messageStore", SQLStoreConfiguration.class)
              .withContext(context)
              .forClass(Message.class)
              .store();