Admins can now reset passwords of regular users

[ShadyMedic]

There's a new button on the account administration page. When an admin clicks it, that user's password is replaced with a new, randomly generated temporary password, which is shown to the admin (who then needs to forward it to the user). Password change will be required after using the temporary password to log in. Passwords of system administrators cannot be reset this way for security reasons. If an admin somehow manages to forget their own password, they'll need to message the webmaster, who will reset the password directly in the database. That should not hopefully ever happen though.

...right?

[ShadyMedic]

This resolves #71 btw.

[ShadyMedic]

Awesome, thank you.