Expanded MockFolder to be a ViewGroup so that it is possible to test views inside folders,
and generally fixed it to service Stapler hierarchies properly so that WebClient-based tests can work.

https://ci.jenkins-ci.org/job/jenkins_main_trunk/2449/testReport/hudson.console/ConsoleAnnotatorTest/testCompletedStatelessLogAnnotation/
junit.framework.AssertionFailedError: expected:<3> but was:<4>
	at junit.framework.Assert.fail(Assert.java:57)
	at junit.framework.Assert.failNotEquals(Assert.java:329)
	at junit.framework.Assert.assertEquals(Assert.java:78)
	at junit.framework.Assert.assertEquals(Assert.java:234)
	at junit.framework.Assert.assertEquals(Assert.java:241)
	at junit.framework.TestCase.assertEquals(TestCase.java:409)
	at hudson.console.ConsoleAnnotatorTest.testCompletedStatelessLogAnnotation(ConsoleAnnotatorTest.java:69)

[FIXED JENKINS-15340] Ask for confirmation before reloading config from disk, as it may be expensive.
First of all, /reload should require POST (also prevents XSS DoS attacks).
Adding <l:confirmationLink> to encapsulate a link that requires confirmation upon clicking.
Allowing a ManagementLink to request confirmation (also implying POST); could be used also for e.g. /quietDown.
Enhancing <l:task> to support confirmation as well, and honoring this in context menu items.

(Not touching the icon since I do not feel like playing with Inkscape; would be a nice pull request for somebody.)

Revert "[FIXED JENKINS-17451] "projects tied to slave" shows unrelated maven module jobs. shows TopLevelItem only."

This reverts commit 3a6de84f.
(Regressed JENKINS-15666.)
Conflicts:

	changelog.html

[FIXED JENKINS-8614] ProcessTreeTest fails on Windows 

[JENKINS-17351] won't fix - clarified help text
Thanks !

[FIXED JENKINS-10891] Page Title French Translation missing

Job" page

[FIXED JENKINS-17451] "projects tied to slave" shows unrelated maven module jobs. shows TopLevelItem only.

[FIXED JENKINS-14067] Polish localization breaks permalink descriptions

[FIXED JENKINS-15365] Invalid translation

Add exception handler for getEnvironmentVariables().