*: Change project name from coreos to flatcar-linux

[krnowak]

This just renames the project from github.com/coreos/mantle to github.com/flatcar-linux/mantle.

[krnowak]

I'm not sure if this change can break access to packet API. Should this stay as github.com/coreos/mantle?

[tormath1]

It looks like a token to identify the generated client in order to keep it across the codebase (and avoid generating new client each time?).
Checking the codebase: https://github.com/packethost/packngo/blob/b666b4ebebb1f0fba2a9ad79428fa79daf0774e2/packngo.go#L334-L342

a regular NewClient will populate this field with packngo lib so I guess we can put whatever we want inside.

[krnowak]

Let's see, if we get some problems with packet, then we can revert this one change.

[tormath1]

Thanks ! That looks good (CI is green) - can we just remove the .travis.yml while we're here and also add a changelog entry under the https://github.com/flatcar-linux/mantle/blob/v0.17.0/CHANGELOG.md#changed section (you might need to rebase to avoid conflict since we released yesterday)

[krnowak]

Thanks for the review. Dropped the file and updated the change log.