adding recipe for creating apache pacemaker primitive

(to be reusable from other barclamps)
What about this:
```
first_of_sorted_plain_ports = crowbar_defined_ports.values.sort_by{ |k| k[:plain] || [65536] }.first
if first_of_sorted_plain_ports.nil? || first_of_sorted_plain_ports[:plain].empty?
  listening_port = 80
else
  listening_port = first_of_sorted_plain_ports[:plain].first
end
```

This should fix all my comments.