OAK-1914 - add workarounds for VARCHAR limit on Oracle

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1605799 13f79535-47bb-0310-9956-ffa450edef68
OAK-1914 - add tests for various property sizes, checking the cutoff between string and BLOB storage

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1605800 13f79535-47bb-0310-9956-ffa450edef68