Simple contract to store Ether.

vault.sol

pragma solidity ^0.4.18;

/** Simple contract to store Ether */
contract Vault
{
    address owner;
    uint balance;
    
    // Modifier for authenticating owner
    modifier ownerOnly(address _owner) {
        require(msg.sender == _owner);
        _;
    }
    
    // Constructor
    function Vault() public payable {
        owner = msg.sender;
        balance = msg.value;
    }
    
    /** Withdraw ether from the contract */
    function withdraw(uint amount) public ownerOnly(owner) {
        require(amount <= balance);
        balance -= amount;
        owner.transfer(amount);
    }
    
    /** Query the balance of the contract */
    function getBalance() constant public returns(uint) {
        return(balance);
    }
    
    /** Query the owner of the contract */
    function getOwner() public constant returns (address) {
        return(owner);
    }
    
    /** Kill the contract and send the remaining ether to the owner */
    function closeVault() public payable ownerOnly(owner) {
        selfdestruct(owner);
    }
    
    /** Increase the balance of the smart contract */
    function deposit() public payable{
       balance += msg.value;
    }
    
    /** Send ether from the contract to an external account or contract */
    function sendPayment(uint amount, address receiver) public payable ownerOnly(owner) {
        require(amount <= balance);
        balance -= amount;
        receiver.transfer(amount);
        
    }
    
    /** Transfer ownership of the contract to an external account */
    function changeOwner(address newOwner) public ownerOnly(owner) {
        require(newOwner != address(0));
        owner = newOwner;
    }
    
    // fallback function
    function () public payable {
        // Rejects normal attempts to send ether from unknown sources
        revert();
    }
}