gRPC support

[clarkezone]

Not sure of gRPC is already supported by this proj, if no please please please consider it :-) FeathergRPC FTW for nice fast bidirectional comms, then i can ditch golang.

[davidfowl]

It is https://github.com/featherhttp/framework/blob/master/samples/GRPC/Program.cs.

@JamesNK has been looking at a terser way to describe GRPC endpoints for smaller services though.

[clarkezone]

For point of note, the gRPC sample doesn't work over an unencrypted pipe.. if you change both client and server addresses to http no dice. Are there plans to add support for configuring an unencrypted transport? Golang makes this trivial to do and it's an essential tool for development purposes.