Be more flexible about location of SSL certs on Linux

[Laeeth]

On Ubuntu 20 my certs is at /etc/ssl/certs/ca-certificates.crt and needs to be copied to /etc/ssl/cert.pem for the plugin to work.

[otrho]

On my Arch under /etc/ssl I have:

lrwxrwxrwx 1 root root    46 Jul 29 02:36 cert.pem -> ../ca-certificates/extracted/tls-ca-bundle.pem

So it installs a symlink itself by the looks of it.

This ServerFault answer is useful. Maybe we can mirror what Go does and look everywhere until we find them. https://serverfault.com/a/722646

[Laeeth]

Above makes sense.

[Laeeth]

closed by #77