Authldap: implement change password in modifyUser
Allow authldap to change password with ldap superuser only if necessary
Hash and salt password with PassHash::ssha

Moved the block closer to the variable use (indent clearer)
Simplify code and remove unreachable check
Merge pull request #674 from axel-angel/authldap_modify-pass

Authldap: implement change password in modifyUser