RUE 0.52 + new Tomcat sensors

New release of RUE (ver. 0.52) which is basically a bug fix version. Update is recommended since several bugs where serious. For more details look at the http://rue.nolimits.ro/downloads/CHANGELOG. Also the sensors are separated now from the RUE core, and two new channels added to the Tomcat sensor which allows now, also, the monitorization of memory and active threads.