SOLR-5746: Bugs in solr.xml parsing have been fixed to more correctly deal with the various datatypes of options people can specify, additional error handling of duplicated/unidentified options has also been added (merge r1612419)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1612433 13f79535-47bb-0310-9956-ffa450edef68