We maintain time stamps locally.

This reverts commit d48e4455.

option one_disk and no_usb are no longer needed when using virtual
In case of virtual option remove kvm module activation

The binary "vmware-mount" has to be installed on the computer
option --virtual must be use with slapbuilder

On boot, slapos script check for Ipv6. If none is found it launch and use OpenVPN

Add possibility to choose  Self hosted image with option --one_disk