The 'has(n.prop) and n.prop = x' idom is outdated, replace the sample.

@systay The new sample raises a new question though, running this sample (fileSize is a long):

```match n where n.fileSize > 0 return n.fileSize;```

I'm also getting _null_ values. Thus nodes _without_ a _fileSize_ property are matched. As far as I can tell, this isn't documented and from other sections of the manual (collections), I see that cypher usually ignores _null_ values. As was the change to make _has(n.prop)_ superfluous for equal comparsion. Shouldn't this extend to other operators too? If _n.prop = x_ compares _false_ if the property is non-existant, shouldn't _n.prop > 0_ also return _false_ if the property doesn't exist?