Consider supporting 'remote' plugins via TCP

[wfarner]

Spurring off from #214 which shed support for TCP in the plugin server and client libraries, we have had several requests for supporting communicating with plugins via TCP. The use case revolves around avoiding a separate body of code and service (the InfraKit plugin) to adapt a system to support InfraKit. For example, if AWS supported an InfraKit API, it would be a boon if users could interact directly with it without the need for a locally-running plugin.