debian: Fill in gecos field for jenkins user

Otherwise when Jenkins runs git, git will complain that the identity is
not set up correctly and will fail.
[JENKINS-3107] Expand an Advanced section if some fields are already customized.
Initial implementation handles only text fields, not e.g. checkboxes.
[JENKINS-3107] Rather than preëxpanding the Advanced area, just show an icon.
[JENKINS-3107] IE 9 fix.
[JENKINS-3107] Icon looks better before button rather than after, for reasons of alignment with the rest of the form.
Trying to demonstrate how to use some more advanced databinding. No luck so far.
Removing debug text.
Apparently cannot have a repeatableHeteroProperty not inside a section/block.
instance, not it.
Get choices from descriptor.
Immutability & copying of lists.
Better formatting.
[FIXED JENKINS-18846] Update symlinks for Maven module builds.
Need to restore the owner of the describable list so that changes in subsequent sessions will be persisted.
(Issue not reproduced here, but was in similar ArtifactManagerConfiguration: 757fe0844ce0d53d08c9d762ddce4b1190ab8cd4.)
@since
[FIXED JENKINS-9637] Fixed the 404 when clicking the testResult on the Project Page when there is only an aggregated test result for a freestyle job. The name of the link is still wrong.
[FIXED JENKINS-9637] Fixed the 404 when clicking the testResult on the Project Page when there is only an aggregated test result for a freestyle job. The name of the link is still wrong.
[FIXED JENKINS-19332]

- set findbugs version to 2.5.2 to avoid:
[WARNING] 'reporting.plugins.plugin.version' for
org.codehaus.mojo:findbugs-maven-plugin is missing. ...

- delete maven-pmd-plugin and maven-checkstyle-plugin (commented out
since more than two years)
Worth recording a UserInterruption even for the anonymous user.
If JenkinsLocationConfiguration.jenkinsUrl is still null, CoreEnvironmentContributor will silently skip several variables.
No obvious fix for that, but at least document it so it is not so surprising.