Instagram test and Instagram node fixes

This is my work on adding the Instagram tests. A few issues might need to be sorted. I'll make comments in-line detailing these.
You probably want a return after this warning since otherwise you'll drop through to the subsequent if/else which means you either continue trying to fetch another page or set node.latestSelfContentID to the (potentially not defined) value of ```idOfSelfReturned``` neither of which seem particularly useful?