Fixed #10. Added support for isUpperCase function

src/main/java/strman/Strman.java

@@ -493,6 +493,17 @@ public abstract class Strman {
         return append(value.substring(0, index), substr, value.substring(index));
     }
 
+    /**
+     * Verifies if String is uppercase
+     *
+     * @param value The input String
+     * @return true if String is uppercase false otherwise
+     */
+    public static boolean isUpperCase(final String value) {
+        validate(value, NULL_STRING_PREDICATE, NULL_STRING_MSG_SUPPLIER);
+        return Objects.equals(value, value.toUpperCase());
+    }
+
     /**
      * Verifies if String is lower case
      *