workspace path displayed as "null" on "Error: no workspace" page

the page used FilePath.getLocal(), which was removed in
19860fa0706bfae87fbf7fadb9411ad90bc7ee5c (12/2006)
[FIXED JENKINS-18836][FIXED JENKINS-18879][FIXED JENKINS-19619] Upgrade trilead-ssh to version with the fix
[FIXED JENKINS-19945] Upgraded bundled plugin versions
add link to changelog
[FIXED JENKINS-19947] Restore historical undocumented behavior of a top-level entry in a ZIP.
Noting that various DirScanner implementations handle this inconsistently.
[FIXED JENKINS-18629]

Consult Descriptor.newInstance() even when proccessing is in the middle
of JSON tree.
(cherry picked from commit d15c15506e8aaa757983a71c868ed58e0fd48827)
[FIXED JENKINS-14336]

Integrating the stapler fix.
updated German localization
purged orphaned messages