[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
Reducing message from stop() to FINE.
Normally this is only printed during functional tests or during in-process restart.
In neither case do we really want to see a log message (i.e. two lines of text) for each plugin in the system being stopped.
Merge branch 'master' of github.com:jenkinsci/jenkins
allow null from the name
Fix typo
the trunk is toward 1.541-SNAPSHOT
Merge branch 'master' of github.com:jenkinsci/jenkins
Correctly restrict read permission in CLIActionTest.serveCliActionToAnonymousUser()
Merge branch 'master' of github.com:jenkinsci/jenkins
Apparently unused copy of something already in hudson.model.Messages.
Improved descriptions of permissions.
Fix indentation
Include jobMain.jelly from actions attached to matrix project
New extra-enforcer-rules published.
[FIXED JENKINS-7285] Fix regression from 1.536