Add curl package to enable Docker healthcheck

[sadmin91]

Is your feature request related to a problem? Please describe.
I am using your image for my personal use.
Actually, I build a custom image (using your image as source) in order to add curl package to create a healtcheck for my swarm service.
I think the addition of this package could help others users.

Describe the solution you'd like
Add curl package on Docker image

Describe alternatives you've considered
Build a custom Docker image to add this package

[jmattheis]

I think we can also include the healthcheck to our docker images.

What do you think of this?

server/docker/Dockerfile

Lines 1 to 7 in 76de16e

	FROM frolvlad/alpine-glibc:glibc-2.31
	WORKDIR /app
	RUN apk add --no-cache ca-certificates tzdata curl
	ADD gotify-app /app/
	HEALTHCHECK --interval=30s --timeout=5s --start-period=5s CMD curl --fail http://localhost:80/health || exit 1
	EXPOSE 80
	ENTRYPOINT ["./gotify-app"]

[sadmin91]

@jmattheis Yes, i'm doing this today.
But why not include curl package on the official Gotify image?

[jmattheis]

Ahh, I'm planning on including this in the official image :D.

[jmattheis]

Fixed with #310