SOLR-4451: SolrJ, and SolrCloud internals, now use SystemDefaultHttpClient under the covers -- allowing many HTTP connection related properties to be controlled via 'standard' java system properties.  (hossman)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1445945 13f79535-47bb-0310-9956-ffa450edef68