When a client uses the buildWithParameters API and request a json output, return the job definition as a json string instead of doing a redirect on the job page.

Conflicts:

	changelog.html

(cherry picked from commit 2e5a7bf4)

This reverts commit 9a1ad74b. The bits
aren't yet synchronized to central apparently.

Conflicts:

	changelog.html

This is also related to [JENKINS-9778].

[FIXED JENKINS-8214] Added a DISCOVER permission to allow anonymous users to be presented the login screen when accessing job URLs

Maven Job

If the -U flag is specified in the goals/options of the build step of a
Maven job, it should be used as well in the parsing step.

[Re-FIXED JENKINS-12457] 'Age' column on 'Test Result' tab may show incorrect value when a test suite divided into multiple junit files

Added testcase and changelog for JENKINS-13214. The actual fix is in 7fba6527

The trick for backward compatibility is in the default implementation
that grants View.READ to those who have access to items.

Use a ping timeout of 3/4 of the ping interval instead of the default
4 minute timeout.
This happens to workaround an issue in the remoting PingThread
implementation which causes the ping to busy wait for the timeout
period instead of keeping the channel alive.