[JENKINS-2673] Clarify that suggestion means polling just once per hour
FingerprintCleanupThread ought to write messages to its saved log file.
Report a warning to build log when the selected JDK cannot be found.
[FIXED JENKINS-17667] Fixed race condition when running tool installers on many slaves at once.
Correcting change made in #1176, which introduced an NPE, to restore original logic merely wrapped in a synchronized block.
Reproduced NPE in new functional test (original bug probably very hard to reproduce).
Merge pull request #1318 from daniel-beck/JENKINS-2673

[JENKINS-2673] Clarify that suggestion means polling just once per hour
@since
Merge branch 'master' of git://github.com/jenkinsci/jenkins
Javadoc comment.
use class="setting-help" in radioBlock.jelly

All other places use this class for a td with help icon.
This improves rendering of the different strategies under "Restrict
project naming"
add missing td elements for table rows without help