Add changeToken methods on MVM and VestedPayment contracts

Author: AugustoL

contracts/LifMarketValidationMechanism.sol

@@ -121,6 +121,13 @@ contract LifMarketValidationMechanism is Ownable {
     funded = true;
   }
 
+  /**
+     @dev Change the LifToken address
+    */
+  function changeToken(address newToken) public onlyOwner {
+    lifToken = LifToken(newToken);
+  }
+
   /**
      @dev calculates the exponential distribution curve. It determines how much
      wei can be distributed back to the foundation every month. It starts with

contracts/VestedPayment.sol

@@ -69,6 +69,13 @@ contract VestedPayment is Ownable {
     token = LifToken(tokenAddress);
   }
 
+  /**
+     @dev Change the LifToken address
+    */
+  function changeToken(address newToken) public onlyOwner {
+    token = LifToken(newToken);
+  }
+
   /**
      @dev Get how many tokens are available to be claimed
    */