Iss1394: add emails to teachers and all admins on deploy

[JRustyHaner]

Fixes #1394

This modification sends an email to each user mentioned as teachers, admins, or owner in initroles in settings.json. It will not send duplicates emails if the email is listed multiple times.

Bonus:

The readout for disk usage will be more accurate and in gigabytes. Showing block sizes is a bit unfriendly.

[JRustyHaner]

@imrryr there isn't any database manipulation here. The code reads data from the settings.json file and sends an email to all emails that are in the initroles array.

[imrryr]

@JRustyHaner Are you just saying that the teacher and admin settings are in the json file, not the database? I would still defer to @MegaGeese and not try to approve this

[JRustyHaner]

@JRustyHaner yes, but I concur. It's best to review code. The email addresses are not pulled from the database. The code that creates the admin users is further up the page and hasn't been changed