Revert the code to set the matchCase parameter using Boolean.valueOf()

The new version in commit 04362d82c1ff9fdaee30b5a43baea1c39058ee0a uses the explicit cast to boolean which throws a ClassCastException. To reproduce, send this to Geoserver 2.4.4 WFS entry point:

| <wfs:GetFeature xmlns:wfs="http://www.opengis.net/wfs" service="WFS" version="1.0.0" outputFormat="GML2"
| xsi:schemaLocation="http://www.opengis.net/wfs http://schemas.opengis.net/wfs/1.0.0/WFS-transaction.xsd" 
| xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
|     <wfs:Query typeName="feature:yourfeature" srsName="EPSG:4326">
|         <ogc:Filter xmlns:ogc="http://www.opengis.net/ogc"><ogc:And>
|             <ogc:BBOX>
| 				<gml:Box xmlns:gml="http://www.opengis.net/gml" srsName="EPSG:4326">
|                     <gml:coordinates decimal="." cs="," ts="">14.1449,40.8071 14.2435,40.8387</gml:coordinates>
|                 </gml:Box>
|             </ogc:BBOX>
| 			<ogc:PropertyIsLike wildCard="%" singleChar="?" escape="!">
|                 <ogc:PropertyName>direzione</ogc:PropertyName>
|                 <ogc:Literal>%Tecchio%</ogc:Literal>
|             </ogc:PropertyIsLike>
| 		</ogc:And></ogc:Filter>
|     </wfs:Query>
| </wfs:GetFeature>

This used to work on GeoServer 2.3.x