Merge pull request #600 from izetex/fix/burnable-token-inheritance

Burnable Token should be inherited from Basic Token issue#596

contracts/token/BurnableToken.sol

 pragma solidity ^0.4.18;
 
-import './StandardToken.sol';
+import './BasicToken.sol';
 
 /**
  * @title Burnable Token
  * @dev Token that can be irreversibly burned (destroyed).
  */
-contract BurnableToken is StandardToken {
+contract BurnableToken is BasicToken {
 
     event Burn(address indexed burner, uint256 value);