SOLR-4462: downgraded Solrj httpcore dependency from 4.2.3 to 4.2.2, and added comments to solrj/ivy.xml describing versioning for httpcomponents httpmime and httpcore, based on httpclient version

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1446713 13f79535-47bb-0310-9956-ffa450edef68