OAK-867: Oak whiteboard

Move the dynamic service trackers from o.osgi to o.spi.whiteboard
and rename from OsgiFoo to WhiteboardFoo since they no longer have
any OSGi dependencies.

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1550218 13f79535-47bb-0310-9956-ffa450edef68