Added New Templates for Xenserver (PV)

Hi,

We have added new templates for Xenserver (PV).
Following is the list of templates :

Centos-6.9 (x86 and x86_64)
Ubuntu-16.04 (x86 and x86_64)
Debian-8.7 (x86 and x86_64)

Regards,
Virtualizor Team.