Fix some typos in Usage Statistics Help pages (en & fr)

[JENKINS-33971] ReverseBuildTrigger.upstream2Trigger cache fix

Also switching to the closure-based method which is not susceptible to bad nesting mistakes.

[FIXED JENKINS-33971] ReverseBuildTrigger.upstream2Trigger was not being reliably calculated during Jenkins startup.

[JENKINS-33826] build history badges styling issues

Use rerunFailingTestsCount rather than @RandomlyFails

Fix advertised JNLP Port

As far as I can figure, the /TcpSlaveAgentListener/ endpoint headers
tell the slaves what the JNLP port is. When I'm running jenkins behind a
proxy (marathon using the mesos plugin, which bridged networking), even
though I was setting the advertised port per a thread[1], it was not
accurately being returned in the header. This patch fixes that.

[1] https://groups.google.com/d/topic/jenkins-mesos/qUrXpDY07TQ/discussion

initializer annotation on instance methods

... which is done by looking for locating & instantiating ExtensionFinders.

This simplifies typical usage of them.

... or else it'll keep running. This can be seen as a large number of zombie threads like the following in the unit test:

"NioChannelHub keys=0 gen=0: Computer.threadPoolForRemoting [#250]" daemon prio=10 tid=0x00007f793d841000 nid=0x3cc1 runnable [0x00007f78e2665000]
   java.lang.Thread.State: RUNNABLE
        at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)
        at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:228)
        at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:81)
        at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:87)
        - locked <0x00000000c50d46d8> (a sun.nio.ch.Util$2)
        - locked <0x00000000c50d46e8> (a java.util.Collections$UnmodifiableSet)
        - locked <0x00000000c50d4690> (a sun.nio.ch.EPollSelectorImpl)
        at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:98)
        at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:102)
        at org.jenkinsci.remoting.nio.NioChannelHub.run(NioChannelHub.java:542)
        at jenkins.util.ContextResettingExecutorService$1.run(ContextResettingExecutorService.java:28)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
        at java.util.concurrent.FutureTask.run(FutureTask.java:166)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:722)

Be quiet

[JENKINS-33546] [JENKINS-33605] Back to Stapler 1.239

Add the .mvn directory and set default Xmx value

Fix typo in hudson/tools/label.jelly

Using the new feature introduced in Maven 3.3.1.
See
https://maven.apache.org/docs/3.3.1/release-notes.html#JVM_and_Command_Line_Options
for more details.

Possibly a long term better solution/first encounter for newcomers. When
people can't build Jenkins because of wrong default memory settings.
Like https://goo.gl/Co9kye

The "Xmx800m" was chosen after looking at last successful ci.j.o builds.
Max memory displayed by Maven being ~730MB. So putting 800 to leave the
build some room so that the GC has less chance to have to chime in too
often.

Make Fingerprint's XSTREAM field public

[FIX WEBSITE-147] Make changelog ratings work on jenkins.io