SOLR-5241: Fix SimplePostToolTest performance problem - implicit DNS lookups

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1523725 13f79535-47bb-0310-9956-ffa450edef68
SOLR-5240: unlimited core loading threads to fix waiting-for-other-replicas deadlock

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1523871 13f79535-47bb-0310-9956-ffa450edef68