ClassMemberNode::create()

Accepts a name and optional value/visibility, returns a new ClassMemberListNode.
Mmmmm I'm conflicted about this living here. On the one hand good coding standards say to specify each class property individually. But php allows for
```php
class MyClass {
  private $privateProperty, $anotherProperty;
}
```

Then on the other hand I don't know about a factory method being on ClassMemberNode here when it returns a ClassMemberListNode. However in same ways it makes sense here because ClassMemberListNode::create would allow you to create a list of members... whereas the one here is returning a list with a single member. Mmmmmm...