Get streams working

[robwierzbowski]

I think the plugin should take the gulp.src stream instead of --source, and output a stream instead of --destination. I'm going to work on that this week.

[robwierzbowski]

Since our ruby tools can't operate on gulp streams we're going to have to write to a temp directory. gulp-ruby-compass works by taking a gulp stream -> writing tmp files -> sass operation -> reading new output files -> back to gulp stream. We'll need to do the same thing.