Exchange contract wrapper address field added

Author: Tameki

zrxkit/src/main/java/com/blocksdecoded/zrxkit/contracts/Contracts.kt

@@ -27,6 +27,8 @@ interface IWethWrapper {
 }
 
 interface IZrxExchange {
+    val address: String
+
     fun marketBuyOrders(orders: List<SignedOrder>, fillAmount: BigInteger): Flowable<String>
 
     fun marketSellOrders(orders: List<SignedOrder>, fillAmount: BigInteger): Flowable<String>

zrxkit/src/main/java/com/blocksdecoded/zrxkit/contracts/ZrxExchangeWrapper.kt

@@ -21,6 +21,8 @@ internal class ZrxExchangeWrapper(
     providerUrl: String
 ) : Contract(BINARY, contractAddress, Web3j.build(HttpService(providerUrl)), credentials, contractGasProvider),
     IZrxExchange {
+    override val address: String
+        get() = contractAddress
 
     private val functionEncoder = RawFunctionsEncoder(gasProvider)