Ownable.sol

pragma solidity ^0.4.16;

/**
 * @title Ownable
 * @dev The Ownable contract has an owner address, and provides basic authorization control
 * functions, this simplifies the implementation of "user permissions".
 */
contract Ownable {


    address owner;

    event OwnershipTransferred(address indexed _previousOwner, address indexed _newOwner);

    function Ownable() {
        owner = msg.sender;
        OwnershipTransferred (address(0), owner);
    }

    function transferOwnership(address _newOwner)
        public
        onlyOwner
        notZeroAddress(_newOwner)
    {
        owner = _newOwner;
        OwnershipTransferred(msg.sender, _newOwner);
    }

    //Only owner can call function
    modifier onlyOwner {
        require(msg.sender == owner);
        _;
    }

    modifier notZeroAddress(address _address) {
        require(_address != address(0));
        _;
    }

}