Execlude *.proto files from the npm package

[xPaw]

I don't think they are needed as only the generated json files should be required, would save a megabyte.

I haven't checked how much removing whitespace from the proto json files would save, but it may help with the parsing speed too.

There's also other stuff that could be excluded: examples, scripts, .github, .idea.

[xPaw]

btw for node-steam-session: since you build from typescript now, the src folder can be ignored there.