Add standard opensource scaffolding

[c-nixon]

In no particular order Add

Docs/legal scaffoding:

• LICENCE(s)
• Contributing.md
• Code of Conduct

Technical stuff:

• CI
• README with build instructions etc
• coverage badge

Rust stuff:

• docs.rs badge
• crates.io badge

Note we don't need all of this up front, but we should at least have the legal stuff and a README

[c-nixon]

WRT licencing: The rust community has mostly standardised around dual licencing Apache2/MIT for maximum compatability/permissivenes. ie contributions come with explicit patent and relicencing grants via the Apache 2 on contributions while also retaining downstream GPLv2 compatability via the MIT licence. I suggest we follow suit.

In terms of what this looks like i the the repo we'd need LICENCE_APACHE and LICENCE_MIT file and we'd probably want a COPYRIGHT file with something like the following (ripped off from the rust-lang/rust repo itself) in it

Short version for non-lawyers:

The logdna-rust project is dual-licensed under Apache 2.0 and MIT
terms.

Longer version:

Copyrights in the logdna-rust project are retained by their contributors. No
copyright assignment is required to contribute to the logdna-rust project.

For full authorship information, see the version control history

Except as otherwise noted (below and/or in individual files), logdna-rust is
licensed under the Apache License, Version 2.0 or
http://www.apache.org/licenses/LICENSE-2.0 or the MIT license
or http://opensource.org/licenses/MIT, at your option.

[nimbinatus]

Hm! Interesting. I like their wording. Nice and clear. And links to licenses versus copy-pasta makes me happy.

The dual-license thing fascinates me. I've only seen a dual open-source and closed-source license set done before, and it was defined very carefully in the codebase. In case anyone else reading this wants a further discussion, here's the Rust discussion: https://internals.rust-lang.org/t/rationale-of-apache-dual-licensing/8952

[c-nixon]

The

Copyrights in the logdna-rust project are retained by their contributors. No
copyright assignment is required to contribute to the logdna-rust project.

is also fairly significant, it means there's none of the awkward copyright assignment form to fill in. It doesn't negatively effect our ability to relicence as the code is MIT/Apache2'd anyway, but just to call out there's an explicit choice being made there.