Labtainers: do not setup the shared folders.

I'm afraid they could delete their Linux home trying to clear something
inside the VM.

But perhaps it could be handy to catch the _xfer archives for the student
submissions.

In that case, maybe we could use the esame user, mount the student_xfer
directory to the Consegna directory, and then use labmanager to retrieve
all the student submissions.

But in their documentations they explain how to do it with Moodle, and
that should be fine for us too...

settings/labtainers.settings

@@ -10,6 +10,9 @@ OS_TYPE="Ubuntu_64"
 # start vm in fullscreen mode
 FULLSCREEN=0
 
+# do not set-up shared folders
+SKIP_SHARED_FOLDERS=1
+
 CREATE_VM=1
 DESCRIPTION="Labtainers"
 #CHIPSET=ich9