OAK-763 Asynchronous indexing
 - moved the scheduler to oak-core
 - refactored/cleaned the code indexing a bit

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1466850 13f79535-47bb-0310-9956-ffa450edef68
OAK-768: Enhance Root API in order to provide information about the ContentSession
Applied slightly edited patch from Antonio: add getContentSession method to Root

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1466851 13f79535-47bb-0310-9956-ffa450edef68