[JENKINS-23271] - Prevent early deallocation of the Proc instance by GC in ProcStarter#join() (#2635)

* [JENKINS-23271] - Prevent the prelimimary deallocation of the Proc instance by GC

It is a hackish way, which likely prevents a preliminary deallocation of the spawned RemoteProc instance, which we see in JENKINS-23271. Proc instance was not actually required in the original code since we were creating and using RemoteInvocationHandler wrapper only, and the theory discussed with @stephenc was that object gets removed by Java8 garbage collector before we get into join().

This fix enforces the persistency of ProcStarter#start() result by adding logging and the enforced volatile field (maybe the last one is not really required, but JIT compiler in Java implementations may be smart enough to skip unused loggers)

This is a pretty old fix from August, which has been soak tested on my instance for several weeks (mid-August => Jenkins World). On the reference instance (just a small Jenkins instance with 4 agents and very frequent builds with CommandInterpreter steps) I saw 2 failures over the period. On the fixed instance - 0. It does not proof anything, but at least the fix was soak tested a bit

* [JENKINS-23271] - Get rid of the procHolderForJoin field

* [JENKINS-23271] - Also put the check into the finally statement as @stephenc proposed

* Remove assert

Stop storing three identical copies of remoting.jar in jenkins.war

Take advantage of LoggerRule to simplify test

[FIX JENKINS-39034] /i18n/resourceBundle should be conform to the w3c standard about locale negotiation (#2594)

* [parseCountry] Extract region/country and variant from the language parameter in case it is bigger then 2 letters. Add tests for both cases.

* [JENKINS-39034] remove debug system out

* [JENKINS-39034] Only if we have 5 or more character we want to get the country - prevent NPE

* [JENKINS-39034] use split since it is more general

* [JENKINS-39034] Only override country and variant if not already set

* [JENKINS-39034] better test cases to test whether the fallback and variant resolving work corret

* [JENKINS-39034] remove duplicate tests and better name existing ones

[JENKINS-39741] - Redirect to login page after authorisation error when checking connectivity to update center and handle any other error.

Polish translations for settings

[JENKINS-39741] - Redirect to login page after authorisation error when checking connectivity to update center and handle any other error.

[FIXED JENKINS-38721, JENKINS-37282] - NPE in "CauseOfInterruption.UserInterruption" when user is missing (#2630)

* [FIXED JENKINS-38721] - Prevent NPE during rendering of "CauseOfInterruption.UserInterruption" when user is missing

It is a regression introduced in JENKINS-36594

* [JENKINS-38721] - Fix typo

[SECURITY-360] 2016/11/16 security fix for 1.625