Failure with multiple module instances

[SimoneMSR]

When the set_position notification is used with a module having multiple instances, the changes are applied only to the first module. I think we should change the row 3 of MMM-Dynamic-Modules.js file from this:

var selected_module = document.getElementById(id);

to this

var selected_module = document.getElementById(module.data.identifier);

In this way it works.