[FIXES JENKINS-19622] Replace hudson.model.Trigger#timer with jenkins.util.Timer, which exposes a ScheduledExecutorService. Up to 10 additional threads will be created to run pending tasks even if running tasks are blocked.

Also, move static initialization of timers to the classes which require them.
We must still initialize and clean up the legacy Trigger#timer
Naming convention
Synchronize access to the ScheduledExecutorService so that we can avoid NPE's during failed startup and lazily initialize it safely.
Null check
Remove meaningless initialization
added ability to get remote disk sizes
Better buttons into popups
Removed commented-out style
[FIXED JENKINS-8815] Fixed issue where CLI required giving Overall read permission to anonymous.
Added test unit.
* Adding a warning message when HudsonTestCase and JenkinsRule reach the configured timeout. This message will be very useful to diagnose test failures caused by timeouts.
* Adding a mechanism to allow users running tests in slow systems can change the default timeout. Now they can change this value using the environment variable "jenkins.test.timeout" expresed in seconds. Example: mvn test -Djenkins.test.timeout=300
Merge pull request #1006 from mrebasti/jenkins-test-timeout
JENKINS-18192 Added last search term to search box
Update changelog for pr #1008
Merge pull request #1005 from christ66/master

[FIXED JENKINS-8815] Fixed issue where CLI required giving Overall read ...

Conflicts:
	core/src/main/java/hudson/cli/CLIAction.java
[FIXED JENKINS-20514] Add a core extension point to allow plugins to contribute to the checking of assigned labels
Fix compiler error
Javadoc
Tidy up after #1005
Merge pull request #1009 from stephenc/master

[FIXED JENKINS-20514] Add a core extension point to allow plugins to con...