mod_cron: Initial commit of periodic task runner
A number of modules now have periodic tasks that need to run, e.g. for
cleaning out old messages or files. This has highlighted a need for
coordinating and optimizing scheduling of such tasks.
For full information on our dependencies, version requirements, and
where to find them, see https://prosody.im/doc/depends
If you have luarocks available on your platform, install the following:
- luaexpat
- luasocket
- luafilesystem
- luasec