describe open-asset command when it requires coffee in same dir
describe open-asset command when it requires javascript in same directory
describe open-asset command when it requires script in another directory
describe open-asset command when it requires js in lib and vendor dir
fix bug that open-asset couldn't open asset includes dot(.) in name
fix bug that open-asset command couldn't open file

When it requires javascript to suffix .js or .coffee
implement open-asset from manifest file