Added the ResultManager#exists method

src/main/java/de/gnmyt/SQLToolkit/manager/ResultManager.java

@@ -128,6 +128,14 @@ public class ResultManager {
         return count;
     }
 
+    /**
+     * Checks if the current result exists
+     * @return <code>true</code> if the current result exists, otherwise <code>false</code>
+     */
+    public boolean exists() {
+        return getRowCount() != 0;
+    }
+
     /**
      * Get a List of all Results
      *