title: Issue with Excel DecisionTable to load from newClasspathResource
body: <p>There is some issue with the implementation of DecisionTable in Excel file, if i am using newClasspathResource to load the excel file, where as if i use newFileResource with path of the file it works fine with the same file.</p>
  
  <p>The Exception is:</p>
  
  <pre><code>Caused by: org.drools.template.parser.DecisionTableParseException: An error occurred opening the workbook. It is possible that the encoding of the document did not match the encoding of the reader.
  at org.drools.decisiontable.parser.xls.ExcelParser.parseFile(ExcelParser.java:85)
  at org.drools.decisiontable.SpreadsheetCompiler.parseResource(SpreadsheetCompiler.java:126)
  at org.drools.decisiontable.SpreadsheetCompiler.getRuleSheetListener(SpreadsheetCompiler.java:185)
  at org.drools.decisiontable.SpreadsheetCompiler.compile(SpreadsheetCompiler.java:172)
  at org.drools.decisiontable.SpreadsheetCompiler.compile(SpreadsheetCompiler.java:167)
  at org.drools.decisiontable.DecisionTableProviderImpl.compileResource(DecisionTableProviderImpl.java:81)
  at org.drools.decisiontable.DecisionTableProviderImpl.loadFromResource(DecisionTableProviderImpl.java:44)
  at org.drools.compiler.compiler.DecisionTableFactory.loadFromResource(DecisionTableFactory.java:37)
  at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.decisionTableToPackageDescr(KnowledgeBuilderImpl.java:404)
  at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.addPackageFromDecisionTable(KnowledgeBuilderImpl.java:374)
  at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.addKnowledgeResource(KnowledgeBuilderImpl.java:766)
  at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:2249)
  Caused by: org.apache.poi.openxml4j.exceptions.InvalidFormatException: Your InputStream was neither an OLE2 stream, nor an OOXML stream
  at org.apache.poi.ss.usermodel.WorkbookFactory.create(WorkbookFactory.java:211)
  at org.apache.poi.ss.usermodel.WorkbookFactory.create(WorkbookFactory.java:168)
  at org.drools.decisiontable.parser.xls.ExcelParser.parseFile(ExcelParser.java:83)
  ... 47 more
  </code></pre>