Merge pull request #149 from axic/strict-address

Ensure ADDRESS_NULL is a strict address literal for Solidity 0.5.0 in testing/Assert.sol

Author: gnidan

lib/testing/Assert.sol

@@ -52,7 +52,7 @@ library Assert {
 
     // Constant: ADDRESS_NULL
     // The null address: 0
-    address constant ADDRESS_NULL = 0x0;
+    address constant ADDRESS_NULL = 0x0000000000000000000000000000000000000000;
     // Constant: BYTES32_NULL
     // The null bytes32: 0
     bytes32 constant BYTES32_NULL = 0x0;