Option added to exclude domains from users to suspend or delete & showing emails in the viewlist

[rogiervandongen]

@melvyng Finally made it to our integration, which will be here soon. This PR hasn't been merged as such, but changes have been incorporated (and changed: Moodle has some rather strict standards your code didno't exactly adhere to, such as using capitals in variable names).

Thanks for your addition (your named in the changelog).