Merge branch 'stable-2.9' into stable-2.10

* stable-2.9:
  Release notes for Gerrit 2.9.4
  Set version to 2.9.4
  Update JGit to 3.4.2.201412180340-r

Conflicts:
	VERSION
	gerrit-extension-api/pom.xml
	gerrit-plugin-api/pom.xml
	gerrit-plugin-archetype/pom.xml
	gerrit-plugin-gwt-archetype/pom.xml
	gerrit-plugin-gwtui/pom.xml
	gerrit-plugin-js-archetype/pom.xml
	gerrit-war/pom.xml
	lib/jgit/BUCK

Change-Id: Ic626d7076156ffcc714266e3c17cdc80fcb62ad9