Describing the previous fix.

This reverts commit c01333c3.
See
https://issues.jenkins-ci.org/browse/JENKINS-20262?focusedCommentId=188404&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-188404
for the discussion why this should be reverted.

Conflicts:

	core/pom.xml

The implementation of the method is rather hard to follow so this certainly needs to be tested!

Sources are UTF-8 so might as well use the raw character when specifying something that will be a part of output.

[FIXED JENKINS-20071] Upgrade bundled versions of credentials and ssh-slaves so we can assume <c:select/> available

[FIXED JENKINS-19926] Add only new env. variables

Add classes and ID's for common elements