Consider making client config backwards and forwards compatible automatically through usage of protobuf

[cameronmeissner]

At the moment, the bootstrap client is configured through raw CLI flags / raw JSON config file. This isn't necessarily forwards or backwards compatible.

In the case where the caller specifies a new CLI flag on an older version of the client, the client invocation would break - instead the client should simply ignore the new config flag that it doesn't recognize.

One solution to this would be to use a versioned protobuf schema and contract instead of raw CLI flags / JSON config file