OAK-1961: Introduce DocumentStoreException

Fix broken cause chain

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1611270 13f79535-47bb-0310-9956-ffa450edef68
OAK-1966 - Add Hint for selecting more performant index in MongoDocumentStore#query

Fix the test to change default value by setting the system property to 120 as we have disabled the feature by default now

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1611275 13f79535-47bb-0310-9956-ffa450edef68
OAK-1972: Async property index update may fail on DocumentMK with more than 100 index changes

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1611277 13f79535-47bb-0310-9956-ffa450edef68