Pressing the user settings button brings up a list of all jellyfin
users, and allows you to add or change their stored email addresses.
Additionally, changed emails.json to use user ID instead of username.
The program automatically converts the file to the new format at start.
The admin page now has the option to send an invite to an email address.
Since there are now two email types (invites and pw resets), the new
sections have been added to config.ini, and email_template and
email_plaintext have been renamed to email_html and email_text
respectively.
Added an extra debugging message to tell the file being read for a
password reset, and changed watchdog form using 'created' events to
'modified', otherwise there may be issues where the file is read before
it is fully written.
