Show page errors only in verbose mode

Phantom sent page errors to stdout, becuse no handler assigned.
I add page.onError handler, which use wappalyzer.log [debug] output

drivers/phantomjs/js/driver.js

@@ -93,6 +93,9 @@
 				page.onConsoleMessage = function(message) {
 					wappalyzer.log(message);
 				};
+				page.onError = function(message) {
+					wappalyzer.log('Page error: ' + message);
+				};
 
 				page.onResourceReceived = function(response) {
 					if ( response.url.replace(/\/$/, '') === url.replace(/\/$/, '') ) {