Do not use implicit type conversion for address literals (#1002)

Uses the explicit address(0) for the zero address

contracts/examples/SimpleToken.sol

@@ -24,7 +24,7 @@ contract SimpleToken is StandardToken {
   constructor() public {
     totalSupply_ = INITIAL_SUPPLY;
     balances[msg.sender] = INITIAL_SUPPLY;
-    emit Transfer(0x0, msg.sender, INITIAL_SUPPLY);
+    emit Transfer(address(0), msg.sender, INITIAL_SUPPLY);
   }
 
 }