Added explicit integer sizes to uint variables in StandardToken (#1004)

contracts/token/ERC20/StandardToken.sol

@@ -86,7 +86,7 @@ contract StandardToken is ERC20, BasicToken {
    */
   function increaseApproval(
     address _spender,
-    uint _addedValue
+    uint256 _addedValue
   )
     public
     returns (bool)
@@ -109,12 +109,12 @@ contract StandardToken is ERC20, BasicToken {
    */
   function decreaseApproval(
     address _spender,
-    uint _subtractedValue
+    uint256 _subtractedValue
   )
     public
     returns (bool)
   {
-    uint oldValue = allowed[msg.sender][_spender];
+    uint256 oldValue = allowed[msg.sender][_spender];
     if (_subtractedValue > oldValue) {
       allowed[msg.sender][_spender] = 0;
     } else {