JavaScript validation to edit.html.php form.

Both new.html.php and edit.html.php have their own javascript
validation file. Although they are very similar, for instance,
when adding a new user, fields like name and email cannot be
the same as the default text that comes with the form. Passwords
cannot be empty either, whereas in edit.html.php, passwords are
not required (in which case the password does not change on
the database), name and email may remain the same, just that
they cannot be empty. In the future, I'll have to come out
with a better solution do avoid code duplication and follow
the DRY principle. At least it is basically working for now...