Change the log level error to warn for the un-deploy errors where use…

…r is not required to do anything

modules/core/src/main/java/org/apache/synapse/deployers/LibraryArtifactDeployer.java

@@ -205,7 +205,7 @@ public void undeploy(String fileName) throws DeploymentException {
 	} else {
 	    String msg = "Artifact representing the filename " + fileName
 		    + " is not deployed on Synapse";
-	    log.error(msg);
+	    log.warn(msg);
 	    throw new DeploymentException(msg);
 	}