v6.21.5. Bugfix. Improvement.

- v6.21.5 January 24, 2013
	- Supports Node v0.9
	- Added `renderSingleExtensions` option
		- Note: currently this will render `src/documents/script.coffee` from
CoffeeScript to JavaScript as intended, HOWEVER the outfile will be
`out/script.coffee` instead of the expected `out/script.js`. We will
likely have to do an extension mapping for single extensions.
	- Added expiremental `docpad-compile` executable
	- Updated dependencies
		- [bal-util](https://github.com/balupton/bal-util) from ~1.15.4 to
~1.16.0