Automate the creation of new images at release time

[laf]

• [x] Hit the GitHub api for the latest release
• [x] Build each image we want to produce
• [x] Publish them automatically.
• [ ] Have travis-ci from librenms/librenms kick start the process on tagged release.

[crazy-max]

releases.sh

@laf Why not using Travis to upload assets ?

[laf]

@crazy-max Wasn't aware of that option. That would mean travis would have to build the actual images as well, would have to test that they support installing virtualbox and packer.

[crazy-max]

@laf Yep you can easily build your images on Travis and push the assets with an encrypted token. I can create a PR, I'm familiar with travis :)

[laf]

Go for it :)