Version 1.1.0

• Fixed Emoji encode & decode bug.
• Improved Long String encrypt and decrypt.
• Added encryptToString and decryptToString, for example:

var xxtea = require('xxtea-node');

var str = "Hello World! 你好，中国🇨🇳！";
var key = "1234567890";
var encrypt_data = xxtea.encryptToString(str, key);
console.log(encrypt_data);
var decrypt_data = xxtea.decryptToString(encrypt_data, key);
console.assert(str === decrypt_data);