Add possibility to monitor metrics through jmx

In order to correlate performance graphs with target system behavior, it could great to add a jmx support to chronos.
As it's possible to analyze garbage collection logs, the idea should be to collect data from specified jmx queries. With this improvement, it will be easy to correlate performance with some specific metrics. For example : jvm memory usage, Tomcat active threads, ehcache hit ratio, dbcp pools activity and specific MBeans.

regards,

Bj