OAK-633: SegmentMK: Hierarchy of journals

Add hierarchy support also for Mongo journals

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1455635 13f79535-47bb-0310-9956-ffa450edef68
OAK-593: Segment-based MK

Make the security tests pass also with SegmentMK

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1455636 13f79535-47bb-0310-9956-ffa450edef68
OAK-527: permissions (wip)

- align SecurityConfiguration#getSecurityHook with #getValidators: pass in workspace name and consequently drop CommitHookProvider.

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1455656 13f79535-47bb-0310-9956-ffa450edef68
OAK-593: Segment-based MK

More careful use of MongoDB write concerns and read preferences

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1455835 13f79535-47bb-0310-9956-ffa450edef68
Merge branch 'trunk' of github.com:apache/jackrabbit-oak into trunk