NFS boot

Set up and test boot with the root filesystem provided via NFS. 
This is normally a prerequisite (standard approach) for automated tests on target.

Steps

• Use a dockerized NFS so that it can be reproduced easily on anyone's system, and also not deeply affect the host system installation 
• Write any configuration to make it work on default systems (this might include some checking of the local network IP, assuming that the hardware is on the same subnet, and more things).
  • That which cannot be handled automatically, make it configurable (environment variables)
• Consider combining a yocto-build-container setup with this NFS container somehow (options in comments) so that the built root filesystem can be exposed by NFS 

AC

• Docker container project set up, configuration stored in a subdirectory of genivi-dev-platform git
• PR sent and merged
• NFS-boot tested on all officially supported platforms