3.30 Remove OwnedProxy (#701)

* Audit fix

* Fix

* Moved variable to storage contract

Author: adamdossa

contracts/datastore/DataStoreProxy.sol

@@ -1,20 +1,20 @@
 pragma solidity ^0.5.0;
 
-import "../proxy/OwnedProxy.sol";
+import "../proxy/Proxy.sol";
 import "./DataStoreStorage.sol";
 
 /**
  * @title DataStoreProxy Proxy
  */
-contract DataStoreProxy is DataStoreStorage, OwnedProxy {
+contract DataStoreProxy is DataStoreStorage, Proxy {
 
     /**
     * @notice Constructor
     * @param _securityToken Address of the security token
     * @param _implementation representing the address of the new implementation to be set
     */
     constructor(
-        address _securityToken, 
+        address _securityToken,
         address _implementation
     )
         public
@@ -26,4 +26,11 @@ contract DataStoreProxy is DataStoreStorage, OwnedProxy {
         __implementation = _implementation;
     }
 
+    /**
+    * @notice Internal function to provide the address of the implementation contract
+    */
+    function _implementation() internal view returns(address) {
+        return __implementation;
+    }
+
 }

contracts/datastore/DataStoreStorage.sol

@@ -3,6 +3,9 @@ pragma solidity ^0.5.0;
 import "../interfaces/ISecurityToken.sol";
 
 contract DataStoreStorage {
+    // Address of the current implementation
+    address internal __implementation;
+
     ISecurityToken public securityToken;
 
     mapping (bytes32 => uint256) internal uintData;