use gulp

supported commands:
- duplo new
- duplo dev (http)
remove unused files
add gulp watch
add duplo build/builddeps
related #2
add duplo release
related #2
add display_help
add exclude feature and fix build bug
add a comment for tips with app name
Only check application code against JSHint
Server should serve from `public`
Ignore component.IO packages
Dev with HTTP, always
fix js[] warnings from our generated code