[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
add missing td elements for table rows without help
Shrinks the header bar from 50px to 40px.
updates to the login/sign up links

- remove the underline to make them a little less heavy
- add hover states - underline + color change.
- remove inline style from login link - is this a security risk, somehow?
new jelly tag <f:helpLink> for displaying help links

The new tag ensures that whenever there is no help available, a blank
table cell is output.
use <f:helpLink> in several tags
Fix keyboard noise in lt_LT translation

I've been trying to fix this with the builtin Javascripty translation dialog for months, with no success so far.
Merge pull request #1338 from mgedmin/patch-1

Fix keyboard noise in lt_LT translation
[FIXED JENKINS-23994] Autocomplete logger names
Merge pull request #1240 from daniel-beck/JENKINS-23041

[FIX JENKINS-23041] Fix systemInfo for offline slaves
Merge pull request #1251 from daniel-beck/JENKINS-14583

[FIX JENKINS-14538] Improve builds dir input validation