[FIX JENKINS-23041] Fix systemInfo for offline slaves

- Don't show link in sidebar
- Make systemInfo page more robust when accessed via URL
[FIX JENKINS-18048] Fix link of SCMTriggerCause from UpstreamCause

- UpstreamCause now tries to initialize upstream causes with the
  correct build in onLoad
- SCMTriggerCause stores build reference and uses its URL to build
  absolute link to changelog
[FIX JENKINS-14538] Improve builds dir input validation
[JENKINS-14583] Move replacement into shared function for reuse
[FIXED SECURITY-133] Restrict access to SCMTrigger status page

The page shows the names and URLs of all jobs currently busy with
polling. This includes jobs users might not regularly be able to
access and might therefore reveal otherwise hidden information.
[FIXED JENKINS-18902] Exclude lower bound of range from changes
Merge branch 'master' into JENKINS-18048

Conflicts:
	core/src/main/java/hudson/triggers/SCMTrigger.java
[FIX JENKINS-22971] Show full project name when in folder.
[JENKINS-14583] Fix tests
[FIXED JENKINS-23636] Indicate node the job workspace is on
[JENKINS-17667] Reverting commit e3952f41c5649c326ace3cc263420a8c287e1e7c.
@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"
change default font to helvetica
[FIXED JENKINS-22641] FileUtils.readFileToByteArray behavior has changed in the latest version of commons-io.
IE compatibility mode tweaks

Set "X-UA-Compatible" meta tag (MSIE browsers only - forces browser compatibility mode)
JS based warning if Document Mode doesn't match IE version (MSIE browsers only)
Remove a closeQuietly call.
Fix NPE when stream is already closed.