mod_cloud_notify: Identify (and immediately push) urgent stanzas, e.g. calls This covers the following things: - A session that appears online, but has a broken TCP connection - Clients such as Siskin and Snikket iOS that require a push for calls to work It allows the stanza to be pushed immediately instead of waiting for the session to hibernate or an ack to timeout. It shouldn't break any existing cases.

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.