change contract name && fix addLiquidity

contracts/intf/IDODOApprove.sol

@@ -0,0 +1,14 @@
+/*
+
+    Copyright 2020 DODO ZOO.
+    SPDX-License-Identifier: Apache-2.0
+
+*/
+
+pragma solidity 0.6.9;
+pragma experimental ABIEncoderV2;
+
+interface IDODOApprove {
+    function claimTokens(address token,address who,address dest,uint256 amount) external;
+    function getDODOProxy() external view returns (address);
+}