Refactor FileInfo#render to be promisy

Also add a unit test for FileInfo
Have blueprints use the expand prompt instead of confirmation
Maintain the live build output in tmp/output.
Merge pull request #458 from mixonic/add-diff

Add some tests, refactor render() to return a promise, use expand for options
Merge pull request #457 from rjackson/live-test-output

Maintain the live build output in tmp/output.