feat(Dockerfile): switch cmd to entrypoint

[SimJoSt]

trafficstars

By using ENTRYPOINT for the default command, it is possible to extend the command with arguments by using CMD in a custom Dockerfile. As the command itself doesn't need to be changed/overwritten with this approach, changes to the location of the binary or command will not break these configurations in the future.

[Pytal]

@SimJoSt checks require a signoff :)

git commit --amend --no-edit --signoff
git push --force-with-lease origin feat/Dockerfile/switch-cmd-to-entrypoint

[icewind1991]

The problem with changing that now is that it would break all existing setups that use the existing CMD overwrite

[Pytal]

The problem with changing that now is that it would break all existing setups that use the existing CMD overwrite

True, I do still think this is a good Docker standard to follow though :) Should we reconsider this when we near 1.0?

[SimJoSt]

@icewind1991 @Pytal @alerque I finally got a grip on all my PRs and updated this one as well. So it is ready to be merged when it's time.