adding helper and utility classes

Author: raghuhit

src/main/java/com/browserstack/client/util/Constants.java

@@ -0,0 +1,11 @@
+package com.browserstack.client.util;
+
+public class Constants {
+  
+  public class Filter{
+    public static final String LIMIT = "limit";
+    public static final String FILTER = "filter";
+    
+  }
+
+}

src/main/java/com/browserstack/client/util/Tools.java

@@ -0,0 +1,9 @@
+package com.browserstack.client.util;
+
+public class Tools {
+
+  // Checks if a string is null or empty
+  public static boolean isStringEmpty(String str) {
+    return (str == null || str.isEmpty());
+  }
+}