mod_log_ringbuffer: Detach event handlers on logging reload (thanks Menel)
Otherwise the global event handlers accumulate, one added each time
logging is reoladed, and each invocation of the signal or event triggers
one dump of each created ringbuffer.
Contributing
============
Guidelines for developers
-------------------------
- Each module should be contained in a folder of its name (e.g.\
`mod_ping/mod_ping.lua`)
- Each module should have a `README.markdown` page in their folder
with a description, usage, configuration and todo sections (feel
free to copy an existing one as a template)
- Commit messages should begin with the name of the plugin they are
for (e.g. `mod_ping: Set correct namespace on pongs`)
Instructions on cloning the repository are at
<https://prosody.im/doc/installing_modules#prosody-modules>