backporting this from the trunk.

We weren't actually enforcing the initialization order at all, as
sorting was based on the plugin name.

$JENKINS_HOME if it exists.

See
http://jenkins.361315.n4.nabble.com/LDAPBindSecurityRealm-groovy-td3584243.html

This change is largely based on changes made by Winston Prakash for Hudson.
The main details about his changes can be found here:

http://issues.hudson-ci.org/browse/HUDSON-8844

I deviated a bit from his changes where it was appropriate (e.g. the
description for allow-signup.html was just plain wrong). Also, there
was a lot of collateral damage from formatting in his changeset, which
I have factored out.

I tested the basic functionality of this change and it seems to be OK.

more gracefully.

[FIXED JENKINS-9807] : [Maven Jobs] Post build deploy task : Deploy with unique versions (timestamp) should be configured by default

ViewGroups like NestedView to override)

When there are absolutely no executors for a specific label, there was an unnecessary delay in provisioning the first node for that label

Added an extension point to allow prodding the NodeProvisioner into taking action faster than it might usually.

[FIXED JENKINS-9845] reduce memory consumption of dependency graph calculation: include maven dependencies with 'unknown' version only if needed.

Fixed JENKINS-9785 : option to run maven in headless mode to avoid boring dock icon to jump and take the focus on OSX

JENKINS-9786 : Jenkins can read repositories definitions from Maven POMs to use the deploy task after the build. It's no more necessary to set/duplicate this information in the job configuration.

[FIXED JENKINS-5044] catch FileNotFoundException if mojos are executed from a classes directory instead from a jar

Pull individual Dependencys out of DependencyGroups we see in
BuildTrigger.execute and make sure to actually kick those builds off
as well, so that we can have two different dependencies (say, for
different parameters) from one upstream project to a single downstream
project.