mod_firewall: spam-blocking.pfw: Remove requirement for invites to have no body Some clients (e.g. Gajim) send a body, which I guess makes sense. The bare JID sender check should already make it hard to bypass this (i.e. a normal client putting muc#user into a normal chat message shouldn't bypass the usual message filters).

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.