Move ArchiveResults into the SQL db to avoid checking the filesystem for every Snapshot output status #513
Description
Right now archivebox.zervice.io is taking 6s+ to load because it has to check the filesystem many times for each row on the page during the template rendering process.
We can load the ArchiveResults entries from the archive/<timestamp>/index.json files into the sqlite3 db. This will eliminate checking each output path on the filesystem every time we want to see whether it completed or not.
