Automatically release on merge to master

[apetro]

It would be better if

• Every merge to master automatically yielded a suitably versioned release

This ought to be possible with discipline, in that

• Commits indicate what kind of change they bring
• Changelog can be updated in the same changeset as the changes it logs

Let's spend none of our time manually running releases and more of our time composing changes worthy of release.

[ChristianMurphy]

Conventional Commits and GreenKeeper have already laid a lot of the ground work needed for this.

There are a number of competing toolsets that can handle actual release phase and changelog generation.

https://github.com/semantic-release/semantic-release
https://github.com/Netflix/unleash
https://github.com/conventional-changelog/standard-version

[ChristianMurphy]

Related to uPortal-Attic/uportal-app-framework#573