update feeratemodel & test case

contracts/lib/FeeRateModelLogicUpdate.sol

@@ -0,0 +1,31 @@
+/*
+
+    Copyright 2020 DODO ZOO.
+    SPDX-License-Identifier: Apache-2.0
+
+*/
+
+pragma solidity 0.6.9;
+pragma experimental ABIEncoderV2;
+
+import {ReentrancyGuard} from "../lib/ReentrancyGuard.sol";
+import {InitializableOwnable} from "../lib/InitializableOwnable.sol";
+
+//for test update
+contract FeeRateModelLogicUpdate is ReentrancyGuard ,InitializableOwnable{
+    //DEFAULT
+    uint256 public _FEE_RATE_;
+    mapping(address => uint256) feeMapping;
+
+
+    event Log(string str, bool result);
+
+    function setSpecificFeeRate(address trader, uint256 feeRate) external onlyOwner {
+        require(trader != address(0), "INVALID ADDRESS!");
+        feeMapping[trader] = 0;
+    }
+
+    function setFeeRate(uint256 newFeeRate) external onlyOwner {
+       _FEE_RATE_ = _FEE_RATE_+ newFeeRate;
+    }
+}