Easier TLS setup

[redecs]

Work to address the easier TLS setup discussed here: #113.

The goals would be to:

• run Fuego in TLS mode
• support custom TLS configuration to have easy option to hook TLS library (for ACME protocol TLS managers that can handle everything automatically) not required not, since you can access Fuego's underling http.Server to set the tls.Config directly.

[redecs]

I made this a draft until I get a better idea on how the integration with a TLS library would look like.

I're looked at autocert but I found it lacking some features.
The next place I looked is Caddy, and I think certmagic it's a better choice for the average developer that would want TLS (and HTTP/2) with Fuego, while of course keeping any of the functionality out of the Fuego code. So I want to include an example on how a setup with Fuego and Certmagic would look like.

Right now I think both library would work by hooking into the fuego.Server.TLSConfig and I thinking to add a WithTLSConfig option, but I want to build an examples and figure out some details. I'll try go get this done in the following days (I need to get a VPS for testing).

[dylanhitt]

I made this a draft until I get a better idea on how the integration with a TLS library would look like.

What you've implemented here is fine for the scope of the issue and you shouldn't worry about the other integration in this Pull Request as I'm sure the next PR will have a lot more discussion 😉

[redecs]

I've added the custom TLSConfig option and removed the RunTLS function I initially added because to me that simplifies the Fuego API for the developers that are using it. We can easily determine if the server should run in TLS mode based on the configured options (via TLSConfig or the provided TLS files). If you don't agree, I think we can roll this back quite easily.

I would like to also contribute on example of TLS server setup to show people how this can be leveraged better but I still have some bits to figure out here.

[redecs]

Added RunTLS back in and removed the options I've previously added. Proper testing for TLS Server. I think we need to updated the test for Run to use a real http client if we want to really test the Run method, not just s.Mux, but I haven't made that change yet. I did add graceful shutdown for both HTTP and HTTPS servers to make sure there are not left overs between test (I had issues when I was running the full test suite).

[redecs]

Also pushed my working example for TLS with ACME Server (Let's Encrypt Staging) using certmagic. Let me know if think it's useful otherwise I can remove it.

[dylanhitt]

Nice, do you mind submitting a separate PR for the example. It's easier on the repo history and makes things easier to find.

[redecs]

@dylanhitt removed the example, will open a new PR with that after we are done with this one, since it requires the code.