Add svn up and gpg --import to 'up'

On each sync (not on each rebase), update keys in svn and import them into gpg.

We have some user complaints around missing and expired keys. This PR addresses them by doing an svn up in the public keys directory and then importing the keys into gpg. We do this on every opass up. Arguably, we might do this instead on every edit because that's the only time it really bites users. But up makes more sense because it's actually an update. Maybe we should do it both times.

I am asking for review here partially because I don't use opass, so I might have missed something in testing.