Release v1.4.0

ATTENTION
This release is broken due to wrongly used images in Dockerfiles (#35)
Do not use this version. Please refer to upcoming version 1.4.1 instead!
You have been warned!!

This release covers the following changes:
(+) Support multi-arch releases (#21)
(+) Add slim image variant without Docker for less disk space usage (#8)

❗ Please check README.md for further details on available Docker tags.

(+) Implement health check (#17)
(+) Add ability to restart Docker Swarm services (#25)
(+) Add feature to concatenate private key and public certificate (#30)
(+) Add ability to dump all certificates if environment variable DOMAIN is not set (#15)

(#) Fix ambiguity when looking up container IDs if two containers contain each other's name (#24)
(#) Fix issue where bash test's brackets were set incorrectly (#30/#31)

Thanks to everyone for contributing to this release!