Add more checkstyle tests

- Lines containing tab(s) after space
- Usage of printStackTrace
- Usage of println
- Add SupressionCommentFilter module

SuppressionCommentFilter can be enabled with
// CHECKSTYLE:OFF
and disabled with
// CHECKSTYLE:ON

smack-extensions/src/test/java/org/jivesoftware/util/Protocol.java

@@ -124,6 +124,7 @@ public class Protocol {
      */
     @SuppressWarnings("unchecked")
     public void verifyAll() {
+        // CHECKSTYLE:OFF
         assertEquals(requests.size(), responsesList.size());
 
         if (printProtocol)
@@ -154,6 +155,7 @@ public class Protocol {
         }
         if (printProtocol)
             System.out.println("=================== End =================\n");
+        // CHECKSTYLE:ON
     }
 
     /**