v1.3.1

Enhancement

• Add isMQTT5 method (f27f85c)
• Add visibility to const constants (#41)
• Add the getArray param to getContents (#42)
• Add Message test (8f7fe30)
• Update Message docs (a41654b)
• Update ProtocolException and Add test (19a6bee)

Fixed

• Fix the topic in Will Message cannot be empty (b56fda1)