Ubuntu-Core OpenSSL certificate authority creation

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Extending system certificates

It would be desirable to allow adding system-wide certificates to an Ubuntu Core system, one example is the way some organisations use Docker with self-signed certs. To enable this we would need to make /etc/ssl/certs/ca-certificates.crt writeable or make it a symlink to something writable (e.g. /etc/writeable). We also need a directory where new certs can be added (probably /var/lib/snapd/certs). Certs could be added on snap installation and removed on snap removal, either by themselves (some k…