Removed "Jenkins" prefix from plugin display names.

Since sorting of plugins in the update manager is based on displayName
this name should not have a common prefix otherwise it's hard to find
a given plugin name.
@CheckForNull
[FIXED JENKINS-21023] Rewrote WorkspaceCleanupThread to determine where workspaces for known items should be, rather than looking for directories that look like they might be workspaces.
One key advantage is that this correctly handles the new default workspace location on the master.
Another is that this allows folders to be correctly skipped, and jobs in folders to be correctly deleted.
A subtler advantage would be handling of configured nondefault workspace locations, and compatibility with WorkspaceLocator.
(Orphaned workspaces from deleted jobs are not removed, but these were not removed before either.)
Merge commit 'cd526e99e63ae362f2d1ce1a04c3c68a38032a5c'
[FIXED JENKINS-21639] Prevent creation of job named '.'.
Merge https://github.com/jenkinsci/jenkins into dot-name-check
[FIXED JENKINS-20730] Use correct folder in log message
Merge pull request #1118 from daniel-beck/fix-ooom-message

[FIXED JENKINS-20730] Use correct folder in log message
Noting #1118
Merge branch 'dot-name-check' of github.com:daniel-beck/jenkins into daniel-beck-dot-name-check
[JENKINS-21639] Noting merge of #1117.
[FIXED JENKINS-17606] Reuse existing fingerprint action if present.
Prevents multiple FingerprintActions.
Merge pull request #1113 from wolfs/fingerprint

[FIXED JENKINS-17606] Reuse existing fingerprint action if present.
fixed misspelling in the Polish translation
It is legitimate (in fact advisable) to have zero executors on the master.
Set the default executor count for a dumb slave to 1, so the user is not forced to type this in.
Merge pull request #1119 from krzysztofr/master

fixed misspelling in the Polish translation
[FIXED JENKINS-21673] Sort authorities on user index page.
Merge pull request #998 from jenkinsci/jenkins-19898

[FIXED JENKINS-19898] test base classes should not be linked to the junit implementation.
safe() also replaces '%' with '_'