Node.js example updated for v0.10 with npm

This PR includes two changes to the Node.js example that make it easier to build and run the example with Node v0.10.26

Previously, there was no package.json file, meaning the user couldn't just run `npm install` and get the required modules.

Small syntax issues in rpx.js meant that the server could not start with Node v0.10.26. Now fixed.

Possible Issue: regression of earlier Node support
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It's likely that this update will cause the code to break with Node 0.8 or earlier. As this release is over a year old, and the examples are expected to be in use for new deploys, this seems like a small concern.