Usage of non-standard naming convention for enumerations

[slimsag]

As discovered in #75 (comment) we use a non-standard naming convention for enumerations (per the official protobuf style guide).

We should switch from the Go style of CamelCase to the official protobuf style of UPPER_CASE instead, and ensure that protobuf-gen-gogo or whatever generates the Go source is emitting these with nice Go names as we desire.

This is important for consistency esp. with regard to supporting other languages.

[dmitshur]

I agree. Our Go code should follow the Go style, and protobuf code should use protobuf style.

That's the right thing to do, even though it means following/knowing 2 styles for us.

But it's going to be friendlier to people using other languages or more familiar with protobufs.