Use the Google naming convention.

[g-easy]

Part of #5.

[g-easy]

We discussed this during today's SIG meeting.

[rnburn]

Can change this to refer just to the Google naming convention, not the full style guide?

What I though we agreed to was core guidelines for the style guide and the google naming convention (since core guidelines doesn't have one)

[g-easy]

@rnburn I'd like to apply most of the style guide, e.g. Output Parameters. How should I change the wording?

Also, we should document exceptions like:

• API should not use features newer than C++11.
• API must be header only.
• Don't use STL types in the API.

[rnburn]

Can we limit this PR to just what we agreed to on the call (which was the naming convention)?

Maybe don't use it to close #5 if you want to further debate the non-naming parts of a style guide.

I would prefer to take CppCore guideline over Google style guide for other parts (they use references for Output parameters).

[g-easy]

Ah, ok. I've updated the PR. Not closing #5.

[g-easy]

Please remind me: how many approvals do I need before it's okay to merge? :)

[reyang]

Please remind me: how many approvals do I need before it's okay to merge? :)

https://github.com/open-telemetry/opentelemetry-cpp/blob/master/CONTRIBUTING.md#how-to-get-prs-merged