Add `0repo proxy` command to serve up local repo via a http proxy
Log feed path when parsing a feed fails
Allow user config to override check_uploaded_archive(archive, url)
Allow config to set ADDITIONAL_CONFIG_TAGS = [(namespace_uri, shortname, [tag1, tag2, ...]), ...]
Fix typo
Tightened security on proxy

- Only listens on the loopback interface
- Refuses to server files outside of "public"