Automatic major / minor / patch increments based on the commit history

[BenLambertNcl]

Ability for CI to automatically publish to npm depending on the commit history. Created as a separate issue from #213.

[BenLambertNcl]

Using semantic-release would give is this functionality, but would require us to use Default angluar semantic commit messages, which might be better in the long run anyway to force a consistent commit style

[JDawes-ScottLogic]

Details from #334 (duplicate):

JDawes-ScottLogic:

semantic-release probably won't work as we're using lerna, but it looks like there's a compatible fork: https://github.com/atlassian/lerna-semantic-release

ColinEberhardt:

If it makes it simpler, I don't think it's a big issue if all of our lerna packages are versioning with the same number. My gut feeling is that this would be simpler from a semver perspective.

Anyhow, feels like a low priority over features / examples / testing at the moment, as long as releases have an easy to follow documented process