Added option for including Sass sourcemaps
Fixed error caused by using spaces instead of tabs
Made command handle actual files instead of stdin
Made plugin only use files instead of stdin when sourcemap is true
v2.7.0. Improvement.

- v2.7.0 December 12, 2013
	- Added support for sourcemaps
		- Thanks to [Jimmy King](https://github.com/jking90) for [pull
request #15](https://github.com/docpad/docpad-plugin-sass/pull/15)