add SwapProxy contract

contracts/SwapProxy.sol

@@ -0,0 +1,88 @@
+pragma solidity ^0.4.18;
+
+import "./LiquidPledging.sol";
+
+
+//   On mainnet extract the values from here: https://developer.kyber.network/docs/Environments-Mainnet/
+//   On ropsten extract the values from here: https://developer.kyber.network/docs/Environments-Ropsten/
+
+contract KyberNetworkProxy {
+    function getExpectedRate(address src, address dest, uint srcQty) public pure returns(uint expectedRate, uint slippageRate);
+    function trade(address src, uint srcAmount, address dest, address destAddress, uint  maxDestAmount, uint minConversionRate, address walletId) public payable returns(uint);
+    function swapTokenToToken(address src, uint srcAmount, address dest, uint minConversionRate) public pure;
+    function swapEtherToToken(address token, uint minConversionRate) public payable returns(uint);
+}
+
+interface ERC20Token {
+    function transfer(address _to, uint256 _value) external returns (bool success);
+    function approve(address _spender, uint256 _value) external returns (bool success);
+    function transferFrom(address _from, address _to, uint256 _value) external returns (bool success);
+    function balanceOf(address _owner) external view returns (uint256 balance);
+    function allowance(address _owner, address _spender) external view returns (uint256 remaining);
+    function totalSupply() external view returns (uint256 supply);
+    event Transfer(address indexed _from, address indexed _to, uint256 _value);
+    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
+}
+
+contract SwapProxy {
+    address public ETH;
+    KyberNetworkProxy public kyberProxy;
+    LiquidPledging public liquidPledging;
+    address public vault;
+
+    /**
+     * @param _liquidPledging LiquidPledging contract address
+     * @param _kyberProxy Kyber Network Proxy address
+     * @param _ETH Kyber ETH address
+     * @param _vault address that receives swap fees
+     */
+    constructor(address _liquidPledging, address _kyberProxy, address _ETH, address _vault) public {
+      if (_vault == address(0)){
+        _vault = address(this);
+      }
+      liquidPledging = LiquidPledging(_liquidPledging);
+      kyberProxy = KyberNetworkProxy(_kyberProxy);
+      ETH = _ETH;
+      vault = _vault;
+    }
+
+    /**
+     * @notice Gets the conversion rate for the destToken given the srcQty.
+     * @param srcToken source token contract address
+     * @param srcQty amount of source tokens
+     * @param destToken destination token contract address
+     * @return exchange rate
+   */
+    function getConversionRates(address srcToken, uint srcQty, address destToken) public view returns (uint exchangeRate)
+    {
+      if(srcToken == address(0)){
+          srcToken = ETH;
+      }
+
+      uint minConversionRate;
+      (minConversionRate, ) = kyberProxy.getExpectedRate(srcToken, destToken, srcQty);
+
+      return minConversionRate;
+    }
+
+    /**
+     * @notice Funds a project in desired token using ETH
+     * @dev Requires a msg.value
+     * @param idReceiver receiver of donation
+     * @param token token to convert from ETH
+     */
+    function fundWithETH(uint64 idReceiver, address token) public payable {
+        require(msg.value > 0, "Not enough ETH");
+
+        (uint expectedRate, uint slippageRate) = kyberProxy.getExpectedRate(ETH, token, msg.value);
+        require(expectedRate > 0, "expected rate can not be 0");
+        uint slippagePercent = (slippageRate * 100) / expectedRate;
+        require(slippagePercent < 15, "slippage exceeds 15%, try a smaller amount");
+        uint maxDestinationAmount = (slippageRate / (10**18)) * msg.value;
+        uint amount = kyberProxy.trade.value(msg.value)(ETH, msg.value, token, address(this), maxDestinationAmount, slippageRate, vault);
+        require(amount > 0, "Not enough tokens for funding");
+
+        ERC20Token(token).approve(address(LiquidPledging), sntBalance);
+        liquidPledging.addGiverAndDonate(idReceiver, token, amount);
+    }
+}