Add Node.js to Elastic Bamboo

Add node capabilities for current version:

• Node.js 0.8 -> 0.8.21 (current latest stable)

Future versions to add will look something like:

• Node.js 1.0 -> 1.0.x
• Node.js 1.2 -> 1.2.x

Need to ensure npm is available and working.

Docs:

• https://github.com/joyent/node/wiki/Installing-Node.js-via-package-manager