The main thing this does (for now) is to make each `Module` inherit
from `AsgMessaging`, and give it a name, etc.  In the future the hope
is that I can also use this to rely on the central `AsgComponent`
mechanisms for `Module` creation.

And a little bit of cleanup as well:
* move the `public:` statement to the top of class
* switch `::StatusCode` into `StatusCode` (drop `::`)
* use the `MsgStream` from `AsgMessaging` consistently