Change visibility of fallbacks to external

contracts/Bounty.sol

@@ -18,7 +18,7 @@ contract Bounty is PullPayment, Destructible {
   /**
    * @dev Fallback function allowing the contract to receive funds, if they haven't already been claimed.
    */
-  function() public payable {
+  function() external payable {
     require(!claimed);
   }
 

contracts/crowdsale/Crowdsale.sol

@@ -61,7 +61,7 @@ contract Crowdsale {
 
 
   // fallback function can be used to buy tokens
-  function () public payable {
+  function () external payable {
     buyTokens(msg.sender);
   }