Added basic test for the Checkstyle-XML-Api
testing the checkstyle-tabs
Merge branch 'master' into checkstyle_xml_api

Conflicts:
	pom.xml
	src/main/java/org/jenkinsci/test/acceptance/plugins/checkstyle/CheckstyleAction.java
	src/test/java/plugins/CheckstylePluginTest.java
Basic tests checking the api of each findbugs, pmd and checkstyle as well als basic checks for the detail build tabs
[JENKINS-22788] Automate gerrit-trigger server start; next: gerrit check
[JENKINS-22788] Automate gerrit review check; new usage; left: proxy cfg
fixed pom xml indentation
indented expected api-xml-files and added comment regarding whitespaces. Changed visibility of a helper method to private
Added JavaDoc for tests.
Reverted file permissions
Merge branch 'checkstyle_xml_api' of https://github.com/jenkins-acceptance-test-group/acceptance-test-harness