Upgrade node.js 0.8 -> 0.10, fix Mac build

This patch does three things:

1. Upgrade node.js from 0.8.x to 0.10.x
2. No longer use a shared v8. This is nice in theory, but results in compatibility problems. For instance to upgrade from .8 to .10 I would also have to upgrade the v8 expression, which is not trivial (got gyp errors trying to do that) and may break other packages that rely on the older v8. node.js comes with v8, so let's just use that version.
3. Fix Mac support