mod_pubsub_serverinfo: Treat public providers as public The opt-in mechanism is to prevent leaking domain names or relationships between small private servers. These are not considerations relevant to public servers. We use the providers.xmpp.net API to fetch a list of known public provider domains.

This module logs events where more than a certain amount of CPU time was
spent.

``` lua
log_cpu_threshold = 0.01 -- in seconds, so this is 10 milliseconds
```

Uses the Lua
[`os.clock()`](http://www.lua.org/manual/5.2/manual.html#pdf-os.clock)
function to estimate CPU usage.