Filtering NH cache log

--HG--
branch : 1.x

src/Orchard.Web/Config/log4net.config

@@ -27,6 +27,11 @@
     <!-- this source is very verbose - setting priority here to avoid flooding trace if root priority is lowered -->
     <priority value="WARN" />
   </logger>
+  
+  <logger name="NHibernate.Cache">
+    <!-- this source is very verbose - setting priority here to avoid flooding trace if root priority is lowered -->
+    <priority value="ERROR" />
+  </logger>
 
   <!-- example of turning on the output from a component or namespace-->
   <!--