replace dockerfile ENTRYPOINT by CMD

[err0r500]

Hello,
This commit just replaces ENTRYPOINT by CMD in the Dockerfile in order to be able to overwrite it if needed.

[mendhak]

Thanks for this. I was able to test out overriding the command like so:

docker run --rm -it mendhak/http-https-echo sh
docker run --rm -it mendhak/http-https-echo ash
docker run --rm -it mendhak/http-https-echo node --version

And the normal container running works too. 👍

[mendhak]

Latest version of the image is up on Dockerhub.

[err0r500]

yes, it's very convenient, especially if you have to wait for another container in a docker-compose (for example)
Thanks for the merge ! ;)