Give both cron-included and non-cron-included users instructions on how to test using --dry-run

[ohemorange]

As pointed out here, we weren't showing users who needed to set up automatic renewal how to test their renewal setup. We should do that. Also, now that we always have users use directory hooks, we should have them test after they've set up the hooks.

Snap, apache (no certonly)

Snap, none of the above (certonly)

Snap, haproxy (certonly)

Pip, apache (no certonly)

Pip, none of the above (certonly)

Pip, haproxy (certonly)

[alexzorin]

1. Given that our example use case for directory hooks is haproxy, it's a little odd that selecting haproxy/pip or haproxy/snapd doesn't show these instructions. Probably just due to the design of the generator.
2. Are we putting the --dry-run instructions below the "directory hooks" instructions intentionally? My first reaction was that it takes a lot of reading to get to it. On the other hand, if it's important for the user to read all that, maybe it's fine as it is.

[ohemorange]

1. Oh no, what?? Yeah that looks like a bug. And we probably should fix Windows as well as some point, now that I'm looking through all our special-cased instructions that aren't just pulling from the file I updated here...

2. Yes, that was intentional. My thought was that if they're testing, they should have it as close as possible to the final setup, including the hooks. I wasn't thinking about importance though, that's a good point. If we swap it, we probably want to tell them to run --dry-run again, what do you think?

[ohemorange]

Well, now it looks a little weird that we're saying "if your webserver is haproxy" when we do know it is, I can fix that.

[ohemorange]

travis??

[ohemorange]

Updated screenshots in the top picture.

[alexzorin]

I think this is pretty good.

Good catch with Windows. I created #720 to track that.