Fix NPE in Launcher.decorateByPrefix

fix tabs

exposing the properties from the base class so that consumers can rely on them regardless of the actual subtype

fixes: JENKINS-12889 Jenkins "Workspace" presents "Run a build" even when Builds are Disabled

Add CANCEL permission that can be granted independently from BUILD perm.

add http header for under firewall enviroment and proxy to cache
Thanks

Conflicts:
	changelog.html

sample : using cloudbees folder plugin
JOB_NAME = foo/bar/job
BUILD-TAG = jenkins-job-number
this change make later to be jenkins-foo-bar-job-number

 Please enter the commit message for your changes. Lines starting

WorkspaceSnapshot now uses the tar.gz format to handle symlinks
correctly.

Tar/untar now correctly supports symlinks.

Fixed the file overwrite problem on Windows.