Fix only assign to `module.exports` but leaves `exports` alone

The `exports` and `module.exports` are not same variable, not l-ref,
but only reference to same value default. When assign to
`module.exports`, we need assign to `exports` too..., otherwise will
lead miss align to node.js idiom.
Fix mqtt part payload spec not match mind model

Extend payload support, auto serialize object to JSON
First try to add feedback service support