OAK-2019 Compact only if needed
 - patch by Jukka with minor additions



git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1619411 13f79535-47bb-0310-9956-ffa450edef68
OAK-2045 Long running JCR session prevent live cleanup in Segment FileStore
 - disabling the test for now, it fails on certain setups

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1619412 13f79535-47bb-0310-9956-ffa450edef68