SOLR-4891: JsonLoader should preserve field value types from the JSON content stream

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1489676 13f79535-47bb-0310-9956-ffa450edef68
SOLR-4891: Fix corruption of BigInteger values

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1489914 13f79535-47bb-0310-9956-ffa450edef68