SOLR-4679, SOLR-4908, SOLR-5124: Text extracted from HTML or PDF files using Solr Cell was missing ignorable whitespace, which is inserted by TIKA for convenience to support plain text extraction without using the HTML elements. This bug resulted in glued words.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1512296 13f79535-47bb-0310-9956-ffa450edef68