New user, some suggestions

[timendum]

Hi, I'm trying this right now and it's very nice.

I have a few suggestions:

• This log should be a debug, it's not a warning, or at least I would like not to see it when the run is OK level=WARN source=rss2email/processor/processor.go:282 msg="remote feed unchanged, skipping"
• The same for sleeping
• The first run fails because the ~/.rss2email folder does not exists, why not create it automatically?
• The first run after adding a new feed is always dumb, because it sends all previous items, can you add an option to immediately mark as seen items only for the new feed? I've contribuied the same in rss2email: /rss2email/rss2email/pull/182
• python sends "List-ID" email header, which is useful for filtering mails in Gmail, can this be added here?

Let me know if I should open split issues or if I can contribuite in any way, I'm very new to Golang, but I can still try if something is easy and agreed on.