Fix issues with running paper.js in node.

We need to export the Object and Array definition into new context, to make Base.isPlainObject() work. See http://nodejs.org/api/vm.html#vm_globals
jsdom uses uppercase values for nodeName with SVG too.
Export view size and set svg attributes in project.exportSVG()
Fix issue with unshared core prototypes along different node scopes.
Implement XMLSerializer for node.
Update node dependencies.
Implement dontLink parameters for View getters.
Check for radial property as well when predicting gradient color type.
Update exportSVG example.