REACH-94 Node positions not updated in nwk

It's the same as "REACH-92 Wrong positions of nodes after opening a file".
It happens because Flood doesn't send messages about moving nodes, therefore in Dynamo all nodes stay where they were created. This behavior is reasonable because sending a node move message after each move would cause to slow performance.
My solution is to update node positions only before saving. It also needs changes in Dynamo (https://github.com/Benglin/Dynamo/pull/178)
Consider using `get('nodes').forEach(function(n){ ... });`  It's much clearer than extracting the models (which you should only do in special circumstances.  See this for more details about the API for backbone collections:

http://backbonejs.org/#Collection-Underscore-Methods