Fix Google Authentication

[JolonB]

Google removed the ability to allow less secure apps, so either the README needs to be updated to a new method (not preferred) or some form of authentication needs to be implemented (preferred).

This should still support other email servers, so shouldn't be adjusted to only support Gmail

[JolonB]

This can be worked around in the meantime by setting the password in the config to a 16-digit app password.

Instructions for doing getting an app password can be found here