Support Node v4.0.0, now that node-canvas is compatible
Support Node v4.0.0, now that node-canvas is compatible

Closes #772

EskenderDev/paper.js,mcanthony/paper.js,nancymark/paper.js,byte-foundry/paper.js,iconexperience/paper.js,EskenderDev/paper.js,iconexperience/paper.js,mcanthony/paper.js,nancymark/paper.js,EskenderDev/paper.js,lehni/paper.js,lehni/paper.js,lehni/paper.js,mcanthony/paper.js,nancymark/paper.js,byte-foundry/paper.js,byte-foundry/paper.js,iconexperience/paper.js