Opennebula aii ONE 4.8 network AR support

Right. In ncm-spma we use `Set::Scalar`, and then set operations:

```perl
my $a = Set::Scalar->new(@{$qimages});
my $b = Set::Scalar->new(@{$myimages});
return $a->symmetric_difference($b);
```

or so. You can also check `Array::Utils` to do the same thing with less code, but I don't know if it's available in EL6.