Added data URLs for Rasters in Node.js
Fixed string equals in Raster data URL for Node.js
Fixed data URLs src disappearing
Explain compact = true in Project#_serialize()
Merge branch 'master' of https://github.com/tranek/paper.js into tranek-master

Conflicts:
	src/item/Raster.js
Clean up @trankek's fix for node a bit.

Fix prepro.js conditionals.
Merge branch 'refs/heads/tranek-master'
Merge branch 'master' of github.com:paperjs/paper.js
Store data in _data rather than on the image itself.