(cherry picked from commit 71600d8b)

Conflicts:
	.idea/compiler.xml
	core/pom.xml
	pom.xml
	war/pom.xml

(cherry picked from commit 9b53643c)

Conflicts:
	pom.xml

See https://github.com/jenkinsci/maven-plugin

(cherry picked from commit f98070d3)

Conflicts:
	maven-plugin/pom.xml
	maven-plugin/src/main/java/hudson/maven/AbstractMavenProcessFactory.java
	maven-plugin/src/main/java/hudson/maven/MavenModuleSetBuild.java
	maven-plugin/src/main/java/hudson/maven/MavenProcessFactory.java
	maven-plugin/src/main/resources/hudson/maven/MavenModuleSet/configure-entries.jelly
	plugins/pom.xml
	pom.xml

Conflicts:
	core/src/main/java/hudson/model/AbstractItem.java
	core/src/main/java/hudson/security/ACL.java
	test/src/test/groovy/hudson/model/AbstractProjectTest.groovy

[FIXED JENKINS-24625] Set background color on input elements

[FIXED JENKINS-21881] System property for disabling X-Frame-Options

Enlarge and move Jenkins head icon

[FIXED JENKINS-6153] Add description for label atoms

[FIXED JENKINS-19764] Ensure parent dir of new builds dir exists.

Since ConsistentHash is written as a mutable class, I think a better way to fit the existing design is to provide a bulk add operation.
It already has several methods to that end, so I just added one more that's needed for our purpose.