Introducing stable branch based on 2.6 to support Jenkins 1.532 LTS line
[FIXED JENKINS-24412][FIXED JENKINS-24410] Save only ItemGroups

(cherry picked from commit 0cb1752ab5d6a0fa7636e6a7a2456508d1013b22)

Conflicts:
	src/main/java/hudson/plugins/jobConfigHistory/JobConfigHistory.java
Always save item groups

(cherry picked from commit d679c9c52d99df7d5776eee98bc4b852ab5a4fae)
Default for saveModuleConfiguration changed to false

(cherry picked from commit 0f70976627703647716f63b841293da6a172b0bd)
Test modified for changed default of module saving

(cherry picked from commit 03d1dae75f714f20e93229d9bb263df5d8821f11)