Allow «Disabled email» and not only «Hide email»

I've done a patch to add this functionality : add radio button in the admin panel to choose between hide, disable or show email field in profile.

the «cas.all.psy.patch» include this feature and spenserj & my correction to the «Modifications to LDAP Integration and LDAP Groups functionality» bugreport
the «cas.psy.patch» include just the feature.

I use ldap_integration code as a template, to do this feature.

Best