Allow all users and/or don't allow superadmin users

A simple patch to make two things:

1. Allow reset password for all users in Sakai (not all the sakai uses types to define users)
2. Avoid ALWAYS to change superuser password independently if the superusers are or not in the correct type. (add a little security)

This is maybe not too interesting to be included in trunk, but can be useful if someone wants this feature.

You need to add in the sakai.properties this:

#resetAllRoles allows this to all roles (false by default)
resetAllRoles=false
#Allow to reset superuser passwords (false by default)
resetSuperusers=false

Sample: To allow all users except superusers (as I need in my sakai)
resetAllRoles=true
resetSuperusers=false

To have it as the sakai actual behaviour (because if a superuser is included in the allowed user types it can be changed)
resetAllRoles=false
resetSuperusers=true

I've not applied it to trunk and tested it but surely patch applies (today...)