Enhance utility method checking if a user-agent is a bot/spider/crawler

Author: laurentpellegrino

src/util.ts

@@ -18,7 +18,10 @@ export class UserAgent {
 
     public static isBot(userAgent: string): boolean {
         const lowerCaseUserAgent = userAgent.toLowerCase();
-        return lowerCaseUserAgent.includes('spider') || lowerCaseUserAgent.includes('bot');
+        
+        return lowerCaseUserAgent.includes('bot') ||
+            lowerCaseUserAgent.includes('spider') ||
+            lowerCaseUserAgent.includes('slurp');
     }
 
 }