Add some functions to the model to retrieve plaintext fields.

Given that the CryptoFactory is seeded with the correct key for a respective user, the plaintext of account login details can be retrieved. In addition, a function for verifying that a password matches has been added. In the case that a user successfully authenticated, the key is by default stored for the duration of the session in the CryptoFactory. If an authentication is unsuccessful, the CryptoFactory key is reset.