LUCENE-5161: set sane default readChunkSizes, make the setter work, and test the chunking

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1512723 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5160: move CHANGES entry to the correct version

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1512728 13f79535-47bb-0310-9956-ffa450edef68