small lua daemon that can send system statistics

Uses the lua mqtt library from: http://git.eclipse.org/c/paho/org.eclipse.paho.mqtt.lua.git

I added the ability to publish retained topics, the changes are in the file "retained_topic.patch".

It only needs lua-5.1, lua-socket and lua-posix.

Type make after checkout and it will produce a debian and openwrt package. The daemon is installed in /usr/sbin and configuration is done in /etc/mqtt-sender/config.lua.

An init-script is also provided. The daemon publishes a retained topic of client/ which is removed when the connection to the mqtt-server is lost.

In addition it publishes the configured topics in intervals under system//module as json strings.

To add new information, just create a new module which gathers the wanted information, add it to the Makefile and create a new package.

To ease development, use the small test.lua which read the config file test-config.lua and calls the configured modules every second. If the configured interval is expired, it prints the modulename and the output of the module or else ist prints "modulename nil" every second for every tested module.