SeleniumMonitor with PhantomJS driver needs gson JAR

If you're using SeleniumMonitor with PhantomJSDriver and your services are failing, with the following appearing in poller.log:

2015-06-09 12:35:30,447 DEBUG [Poller-Thread-1-of-30] o.o.n.p.m.SeleniumMonitor: Selenium sequence failed: Failed:  com/google/gson/JsonParseException
 Cannot invoke method quit() on null object

Then you probably need to add the following JAR to /opt/opennms/lib and restart:

https://search.maven.org/remotecontent?filepath=com/google/code/gson/gson/2.3.1/gson-2.3.1.jar

It appears the PhantomJSDriver POM does not declare this dependency. We should probably add it to the protocols/selenium POM?

This issue references support ticket https://mynms.opennms.com/Ticket/Display.html?id=3887