add UUID to root context

part of #435 

* enriches the root context
* fixes Loggable recipient in NetMessage object

We probably want to officially deprecate the command context and use the context.Context to shuttle the data (config path, etc.) across the boundary (main -> commands lib -> ipfs command). Yet another TODO.
`nodeFunc` reads more like a getter. maybe either
- `constructNodeFunc`
- make the function check

```Go
if i.node != nil {
  return i.node, nil
}
```