vincular bibliotecas con contratos inteligentes

He creado una biblioteca e importado en mi contrato. No puedo vincular la biblioteca en el archivo de implementación.

solución necesaria. gracias en adv

pragma solidity ^0.4.2;

library StringUtils {
    /// @dev Does a byte-by-byte lexicographical comparison of two strings.
    /// @return a negative number if `_a` is smaller, zero if they are equal
    /// and a positive numbe if `_b` is smaller.
    function compare(string _a, string _b) returns (int) {
        bytes memory a = bytes(_a);
        bytes memory b = bytes(_b);
        uint minLength = a.length;
        if (b.length < minLength) 
        minLength = b.length;
        //@todo unroll the loop into increments of 32 and do full 32 byte comparisons
        for (uint i = 0; i < minLength; i ++) {
            if (a[i] < b[i])
                return -1;
            else if (a[i] > b[i])
                return 1;
        if (a.length < b.length)
            return -1;
        else if (a.length > b.length)
            return 1;
        else
            return 0;
        }
    }
    /// @dev Compares two strings and returns true iff they are equal.
    function equal(string _a, string _b) returns (bool) {
        return compare(_a, _b) == 0;
    }
    /// @dev Finds the index of the first occurrence of _needle in _haystack
    function indexOf(string _haystack, string _needle) returns (int) {
        bytes memory h = bytes(_haystack);
        bytes memory n = bytes(_needle);
        if (h.length < 1 || n.length < 1 || (n.length > h.length)) 
            return -1;
        else if (h.length > (2**128 - 1)) 
            return -1;                                  
            else {
                uint subindex = 0;
                for (uint i = 0; i < h.length; i ++) {
                    if (h[i] == n[0]) {
                        subindex = 1;
                        while (subindex < n.length && (i + subindex) < h.length && h[i + subindex] == n[subindex]) {
                            subindex++;
                        }   
                        if (subindex == n.length) {
                        return int(i);
                    }
                }
            }
            return -1;
        }   
    }
}

mi contrato

import "./StringUtils.sol";
contract SaveData is Whitelist {
function verifyHash(address publicAddress, string hashstring) external returns (string) {
        require(StringUtils.equal(data[publicAddress],hashstring));

    }
}

en despliegue: -

var WhiteList = artifacts.require("./Whitelist.sol");
var SaveData = artifacts.require("./SaveData.sol");
var StringUtils = artifacts.require("./StringUtils.sol");

module.exports = function(deployer) {
  deployer.deploy(WhiteList);
  deployer.deploy(SaveData);
  deployer.deploy(StringUtils);
};