updates for zotac zbox en72070v with Ubuntu 18.04

[aksgibm]

vs graphic driver issue on 18.04 installer:

1. flash iso file to USB memory, and mount it.
2. open /boot/grub/grub.cfg with text editor.
3. add following snippet:
   menuentry "Ubuntu (safe graphics)" { set gfxpayload=keep linux /casper/vmlinuz file=/cdrom/preseed/ubuntu.seed boot=casper only-ubiquity quiet splash nomodeset --- initrd /casper/initrd }
4. boot from usb memory and choose "Ubuntu (safe graphics)".
5. install Ubuntu (typical settings)
6. reboot and press shift-key to enter the grub menu.
7. choose "Advanced options for Ubuntu".
8. launch Ubuntu
9. install nvidia driver.
   sudo add-apt-repository ppa:graphics-drivers/ppa sudo apt-get update sudo apt-get install nvidia-driver-440
   follow the instruction of this repository but after 00-install-nvidia-driver.sh

[aksgibm]

refer this to install x11vnc on ubuntu
https://github.com/CMU-cabot/cabot-ros-setup/blob/master/18-setup-vnc.sh