Adding the ADDON_JARS option which is needed for weblogic client jars.

This is to support additional Jars that can be sent during execution of the jmxtrans. This is needed for weblogic connection as there is a proprietary jar that needs to be included for it to connect to a running weblogic server.

Sample weblogic connection
{  
   "servers":[  
      {  
	"host": "sfn.abc.com", 
        "port":7003, 
        "url": "service:jmx:t3://sfn.abc.com:7003/jndi/weblogic.management.mbeanservers.domainruntime", 
        "username": "weblogic",
        "password": "dummyPass", 
        "protocolProviderPackages": "weblogic.management.remote", 
 ...