Test result page keeps identifying tests as age 1

If a test has not been viewed, the age will keep being 1.
This is because getFailedSince()/failedSince is lazy loaded.
Without having viewed the CaseResult that method is never
called and the prev.failedSince returns '0' which may or may
not be accurate.
http://jenkins.361315.n4.nabble.com/Problem-with-Age-column-on-Test-Results-tab-td3172208.html
[JENKINS-20739] Filter descriptors before adding them to hetero-list.

This allows implementations of DescriptorVisibilityFilter to hide items
with descriptors from users to prevent them from being added via the UI.

This is already implemented in /lib/hudson/newFromList/form.jelly, but
nowhere else.
Added logging when filtering descriptors.
updates German translation

Since 'Job' was renamed to 'Item', this translation should be updated
Update sidepanel_de.properties
Update newJob_de.properties
Abstract username case sensitivity into an extension point
[JENKINS-22247] Provide an extension point to define user id case sensitivity contract

* Fix up bad merge
Use a dedicated descriptor
Updating the pull request in light of comments

- Removed the Legacy strategy completely
- Moved the strategy to an aspect of the security realm
- Separated the strategy for Users from Groups because... well it might be necessary for some
- Moved IdStrategy from inner class of User into top level class
[FIXED JENKINS-22395] Attempt to double-delete a Run probably caused by getNextBuild sometimes returning a build which was already deleted.
Remove repo file from RPM. https://issues.jenkins-ci.org/browse/JENKINS-22690
[FIXED JENKINS-22698] Add indicator that build queue is filtered.
[FIXED JENKINS-22699] Add option to archive only if successful
Updated w.r.t. pull request review comments
Fix test
[FIXED JENKINS-22720] Only call getAllItems in recursive ListView
[maven-release-plugin] prepare release jenkins-1.561
[maven-release-plugin] prepare for next development iteration
updated changelog for release