Provide support for customizing the name of the sender on notification emails

[hispanic]

In the notification emails sent out by Staticman, the email address of the sender may be customized via the email.fromAddress property in the JSON config file. However, the name of the sender is hard-coded to be "Staticman" and is not exposed for customization. Having emails from "Staticman" arrive in subscribers' inboxes is awkward, as few/none are aware of what Staticman is. The name of the sender should be customizable.