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 (merged trunk r1446713)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1446714 13f79535-47bb-0310-9956-ffa450edef68