vagrant: sync Tutorials folder into vbox

[cgundogan]

This addition to the Vagrantfile syncs the parent folder of RIOT into the vbox machine with the name Tutorials, which is necessary for the RIOT Tutorial [1] to work. Otherwise, it is always necessary to clone the tutorials folder seperately into the vbox machine.

How does this work:
The Vagrantfile defines a primary RIOT machine, which is booted and ssh'ed into with vagrant up and vagrant ssh. To boot the tutorials machine definition and ssh into it, you must use vagrant up tutorials and vagrant ssh tutorials. This tutorials machine will sync the RIOT folder to $HOME and also the Tutorials folder, which is the parent folder if cloned from [1].

[1] https://github.com/RIOT-OS/Tutorials

[cgundogan]

amended a small fix (wrote tutorial instead of tutorials) and added a name for the machine

[smlng]

this basically works, ACK from myside

Two minor issues:

1. following error is raised when another RIOT VM runs parallel to tutorials:

Vagrant cannot forward the specified ports on this VM, since they
would collide with some other application that is already listening
on these ports. The forwarded port to 4242 is already in use
on the host machine.

Should separate network config with differing ports here.

1. if someone runs vagrant up tutorials in RIOT root dir (not from tutorials), then this would expose any upper folder (../) of RIOTBASE into the VM.

Though I understand the latter to be desired/needed for the tutorials.

[cgundogan]

@smlng good hint, regarding the ports, let's try to fix that in a follow-up PR

[smlng]

@cgundogan hope to see this one soon 😁 ACK and GO then.