Caddy version: v2.2.0 h1:sMUFqTbVIRlmA8NkFnNt9l7s0e+0gw+7GPIrhty905A=

I am trying to pass pem-encoded client certificate to proxied service via a X-SSL-Cert header, like so:

sub.example.com {
    reverse_proxy 127.0.0.1:8000 {
        header_up X-SSL-Cert {http.request.tls.client.certificate_pem}
    }

    tls {
        client_auth {
            mode require
        }
    }
}

I like how Simplepush presents a couple of different ways to generate push messages on their website:

https://simplepush.io/#libraries

How about having a similar feature directly in the server GUI? That would include the bits documented here https://gotify.net/docs/pushmsg

A parametrized option to set the blocksize would be useful to experiment with. As quorum is used in a private setting I think this option should be available

E.g. accept missing leading 0

In osx/updater/updater.go, we're referencing an ancient Go package, which has moved to a new location. Right now, the updater doesn't build (should we test this on travis?).

Behavior of the program

1. A tooltip does not use the same css as other tooltips.
2. Toolips get cut off when window is narrow.

Expected behavior

1. Tooltips should use identical css.
2. Tooltips shouldn't get cut off.

To Reproduce

1. Go to 'Settings' and place mouse over the questionmark icon

Screenshots
![screenshot3](https://user-images.githubusercontent.com/4