Add the release schedule page, a news to inform about that, and update the board reports page.

git-svn-id: https://svn.apache.org/repos/asf/karaf/site/trunk@1604212 13f79535-47bb-0310-9956-ffa450edef68
Add a couple of articles

git-svn-id: https://svn.apache.org/repos/asf/karaf/site/trunk@1604214 13f79535-47bb-0310-9956-ffa450edef68