Setting tag plewww-5.2-9

Setting tag plewww-5.2-9
not too clean patches for r2lab:
* search for a file named /etc/planetlab/php/person-registration.txt
that can override the text message for individuals registration
* do not list sites that have the disabled_registration tag set
when listing them for individuals registration
remove omf-friendly checkbox in slice-creation dialog
comment out {Min,Max}SpareServers settings in httpd config