Update to upstream version 1.7.1
Details:
- New features and bug fixes (many related to acme) in the 1.7 branch, see https://github.com/containous/traefik/releases/tag/v1.7.0
- Additional bug fixes sind 1.7.0 release, see https://github.com/containous/traefik/releases/tag/v1.7.1
MFH: 2018Q4