Update remaining contracts to use new transaction schema

contracts/exchange/contracts/examples/ExchangeWrapper.sol

@@ -61,6 +61,7 @@ contract ExchangeWrapper {
         LibZeroExTransaction.ZeroExTransaction memory transaction = LibZeroExTransaction.ZeroExTransaction({
             salt: salt,
             expirationTimeSeconds: transactionExpirationTimeSeconds,
+            gasPrice: tx.gasprice,
             data: data,
             signerAddress: makerAddress
         });
@@ -99,6 +100,7 @@ contract ExchangeWrapper {
         LibZeroExTransaction.ZeroExTransaction memory transaction = LibZeroExTransaction.ZeroExTransaction({
             salt: salt,
             expirationTimeSeconds: transactionExpirationTimeSeconds,
+            gasPrice: tx.gasprice,
             data: data,
             signerAddress: takerAddress
         });

contracts/exchange/contracts/examples/Whitelist.sol

@@ -134,6 +134,7 @@ contract Whitelist is
         LibZeroExTransaction.ZeroExTransaction memory transaction = LibZeroExTransaction.ZeroExTransaction({
             salt: salt,
             data: data,
+            gasPrice: tx.gasprice,
             expirationTimeSeconds: uint256(-1),
             signerAddress: takerAddress
         });

contracts/exchange/contracts/src/MixinExchangeCore.sol

@@ -361,11 +361,14 @@ contract MixinExchangeCore is
                 orderInfo.orderHash,
                 makerAddress,
                 signature
-            )) {
+            )
+        ) {
             if (!_isValidOrderWithHashSignature(
                     order,
                     orderInfo.orderHash,
-                    signature)) {
+                    signature
+                )
+            ) {
                 LibRichErrors.rrevert(LibExchangeRichErrors.SignatureError(
                     LibExchangeRichErrors.SignatureErrorCodes.BAD_SIGNATURE,
                     orderInfo.orderHash,