Adjust JIRA component.

According to https://wiki.jenkins-ci.org/display/JENKINS/2014+JIRA+Components+Refactoring
Merge pull request #272 from KostyaSha/upd

Adjust JIRA component.
Implement ancestry build chooser
Improve test coverage slightly
Make AncestryBuildChooser fields immutable
Update package name of AncestryChooser groovy config file
Fixed JUnit tests for JENKINS-24133 on Windows
Merge remote-tracking branch 'upstream/master' into master-remove-jgit-and-guice-repos-from-pom