Update node.py to acquire Object Attributes

[davecabio]

Is your feature request related to a problem?

Yes. Currently the plugin doens't get the attributes included in an object, even if them are others IoC (Indicator of compromise).

Describe the solution you'd like

It's enough to change the following line in node.py
attributes = event.get('Attribute', [])

with this:

attributes_object = map(lambda x: x['Attribute'], event.get('Object',[]))
attributes_standard = event.get('Attribute', [])
attributes = attributes_standard + attributes_object[0]

And then, mineme-misp will get event the IoC included in the objects list.