Fix VirtualBox settings for functional Ethernet

[Erriez]

The following VirtualBox VM configuration settings are required in order to suppress warnings and functional DHCP at boottime:

• --vram: Minimum supported video RAM is 20MB
• --graphicscontroller: VirtualBox GUI strongly recommends vmsvga
• Default settings when creating a new VM (and fix Ethernet):
  • --acpi=on
  • --ioapic=on
  • --rtcuseutc=on

Before the fix:

ping <IP>
connect: Network is unreachable, cannot shutdown VM as it is waiting for link up.
Graphics warnings shown in VirtualBox GUI.

After the fix:

Ping and shutdown works as expected.
No warnings in VirtualBox GUI.

closes #7