Service improvements and example

# mw-tcp-service

__Don't pull this just yet!__ I'm not done with it :grin:

This is going to be some base classes and maybe DSLs for creating services, as well as a little Hello, World! service example.

## Todo

* [ ] `TcpService` base class for TCP-connection based services
* [ ] _Maybe_ service groups
* [ ] _Maybe_ more commenting