mod_compat_roles: New module providing compat shim for trunk's new role API The new role API is translated to is_admin() calls on older versions. On newer versions (which have the role API) this module does nothing. It allows modules to drop their use of is_admin() (which is not available in trunk) and switch to the new role API, while remaining compatible with previous Prosody versions.

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.