Configuring Chrome DevTools compile time configuration

[holsee]

Following on from the discussion of System Environment Variable versus App Config for configuration of the Compile Time protocol target: https://github.com/andrewvy/chrome-remote-interface/pull/27

@andrewvy has expressed concern regarding the use of environment variable as a compile-time configuration option to signal which Chrome DevTool protocol version to be selected. There is merit in this objection so I am opening this issue for further discussion and resolution.

I am open to the use of config.ex (as @andrewvy points out this is what Logger uses to configure its macros) and would be happy enough with this to change as long as a sensible default remains when the configuration is not present on the inclusion of the CRI dependency 👍 .