Modifying Instagram query node behaviour

Hi @knolleary here are my changes made for the Instagram query node's behaviour as discussed today. As you're planning to do a release today, I decided to deliver my pull request early. Do note however that the unit tests were mainly fine-tuned for the query node's previous behaviour.

They are to be re-written to deal with the input node instead. Additionally new query node tests are to be written. I'll start that piece of work as soon as I can, however it might not be completely done by the end of today. I hope that's OK!

Additionally as the query node features might be enhanced too in our next iteration, maybe it's best to hold on writing the tests until everything is finalised?