[BIServer 6590] Added export file types to support .locale files

Nick suggested this needs to be pluggable
<property name="localeExportList">
	<pen:list class="org.pentaho.platform.api.engine.IContentInfo">
		<pen:attributes>
			<pen:attr key="supportsLocales" value="true"/>
		</pen:atributes>
	</pen:list>
</property>