[TokenVesting] Remove VestedTokenMock

test/helpers/VestedTokenMock.sol

@@ -1,11 +0,0 @@
-pragma solidity ^0.4.11;
-
-import '../../contracts/token/VestedToken.sol';
-
-// mock class using StandardToken
-contract VestedTokenMock is VestedToken {
-  function VestedTokenMock(address initialAccount, uint256 initialBalance) {
-    balances[initialAccount] = initialBalance;
-    totalSupply = initialBalance;
-  }
-}