Adjust JIRA component.

According to https://wiki.jenkins-ci.org/display/JENKINS/2014+JIRA+Components+Refactoring
Added behavior: "Polling ignores commits with certain messages"
Added MessageExclusionTest test case.
Migrate to abstract. Added UserExclusionTest.
Optimize Pattern matching.
Fix help page. Not literal, but Pattern.
Don't use deprecated method.
Support multiline comments matching.
Extend description with multiline matching.
Findbugs should not warn about intentional null Boolean return in MessageExclusion

Since isRevExcluded intentionally returns null in all cases, and is
excluded explicitly in the other cases, it is safe to exclude it in
this new case as well.
Add TestGitRepo constructor from master

Needed by the Polling ignores commit by message test case
Fixed JUnit tests for JENKINS-24133 on Windows
Merge pull request #274 from pbaranchikov/detachedSha1

Fixed JUnit tests for JENKINS-24133 on Windows
[maven-release-plugin] prepare release git-2.2.9
[maven-release-plugin] prepare for next development iteration
Update to git-client-plugin 1.12.0 [JENKINS-25639]

Revision.equals() needed to complete the fix of JENKINS-25639
Update to mockito 1.10.13
Update to JGit 3.5.2 to match git-client-plugin 1.12.0
DefaultBuildChooser.getCandidateRevisions() now returns Set<Revision> to filter duplicates.
[FIXED JENKINS-25639]
test DefaultBuildChooser with unknown SHA1