Include the link for the jmxtrans tool

The jmxtrans is a tool  to connect to multiple JVMs and to query them for their attributes via JMX. Its query language is based on JSON, which allows non-Java programmers to access the JVMs attributes. Likewise, this tool supports different output writes, including [Graphite](http://graphite.wikidot.com), [Ganglia](http://ganglia.sourceforge.net), [StatsD](https://github.com/etsy/statsd), among others.