fixes reference count leaks.

3a38a67c that causes update center to
fail to accept updates.

Enhancements for Maven dependency graph

[FIXED JENKINS-10367] Maven modules which are not buildable should be excluded from the dependency graph

[FIXED JENKINS-10366] choose most 'relevant' job for dependency graph if multiple jobs are building the same maven module

to the master.

Conflicts:
	changelog.html

instead of @TagLibraryUri("/lib/jenkins")

deleted encoding-less variant of readFirstLine according to https://github.com/jenkinsci/jenkins/commit/4ee8d6890c354e67daeb5f55806c16f6986b32c3#core/src/main/java/hudson/util/IOUtils.java-P13