Add returnPurchase function to Crowdsale contract

Author: AugustoL

contracts/LifCrowdsale.sol

@@ -387,6 +387,22 @@ contract LifCrowdsale is Ownable, Pausable {
     msg.sender.transfer(toReturn);
   }
 
+  /**
+     @dev Allows the owner to return an purchase to a contributor
+   */
+  function returnPurchase(address contributor)
+    public hasEnded onlyOwner
+  {
+    require(!isFinalized);
+
+    uint256 toReturn = purchases[contributor];
+    assert(toReturn > 0);
+
+    purchases[msg.sender] = 0;
+
+    msg.sender.transfer(toReturn);
+  }
+
   /**
      @dev Finalizes the crowdsale, taking care of transfer of funds to the
      Winding Tree Foundation and creation and funding of the Market Validation