I guess this plugin requires jsp:
Dec 15, 2014 9:37:29 AM jenkins.InitReactorRunner$1 onTaskFailed
SEVERE: Failed Loading plugin monitoring
java.io.IOException: Failed to initialize
at hudson.ClassicPluginStrategy.load(ClassicPluginStrategy.java:369)
at hudson.PluginManager$2$1$1.run(PluginManager.java:357)
at org.jvnet.hudson.reactor.TaskGraphBuilder$TaskImpl.run(TaskGraphBuilder.java:169)
at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:282)
at jenkins.model.Jenkins$7.runTask(Jenkins.java:899)
at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:210)
at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:117)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.IllegalStateException
at org.eclipse.jetty.servlet.ServletContextHandler$Context.addListener(ServletContextHandler.java:1216)
at org.jvnet.hudson.plugins.monitoring.HudsonMonitoringFilter.init(HudsonMonitoringFilter.java:23)
at hudson.util.PluginServletFilter.addFilter(PluginServletFilter.java:75)
at org.jvnet.hudson.plugins.monitoring.PluginImpl.start(PluginImpl.java:57)
at hudson.ClassicPluginStrategy.startPlugin(ClassicPluginStrategy.java:377)
at hudson.ClassicPluginStrategy.load(ClassicPluginStrategy.java:366)
... 9 more