Only compile product files and fix tests
Unit test that makes sure non-product scripts aren't built
Force file deletion when cleaning up product files
Using Enumerable#any? instead of inject
Making the return value of ManifestDir#build consistent with the return value of ManifestFile#build
Fixed return value of ManifestFile#build
Merge pull request #4 from lopatin/alex_only_build_product_files

Don't build styles and scripts if they aren't in products