mod_storage_xmlarchive: Insert micropauses in long-running queries Allows other processing to be interleaved with long-running queries. Drops 0.9 support since it requires util.async, but 0.9 really should be EOL by now.

This module lets you block connections to any remote servers not on a
whitelist.

``` {.lua}
s2s_whitelist = {
    "example.org",
}
```