To have a less source based, and more consumable example of structures,
this is an initial pass at protobuf structures for the structures in the
specs golang source.

There is some exercise needed in platform specific structures.

For the sake of example, the Makefile defaults to outputing golang
source, but has a 'c' target (`make c`) for C source, a `make py` and
`make all` target.

This User structure does not map to the cleanliness of the current go
structure, but will allow the definition to be all in one place,
regardless of the host that is doing the compilation.

All field rules to `optional` for now. Per vish and the docs,
https://developers.google.com/protocol-buffers/docs/proto?csw=1#specifying-field-rules
"! Required Is Forever"

There are a couple of concessions, but is pretty much lined up.

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

https://developers.google.com/protocol-buffers/docs/style?hl=en

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

Let the user decide the value.

opencontainers#179 (comment)

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

per opencontainers#179 (comment)

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

Now the default make target shows json output from the example.go
source.

Consolidated the protobuf files due to a cyclic import issue.

Cleaned up outputs to source respective outputs directories.

Added a `cpp` target.

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

* a more field out config structure
* display using the jsonpb library
* display the binary proto message

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>