long pure number string exception

[bennuXu]

if the xml contains an element with value is a long pure number string,big than MAX_SAFE_INTEGER,
the condition on line 106 "if(rest/1!=rest)" will treats string value as an number, gets a wrong value.

sample:

var xml2json = require('node-xml2json');
var xml = '<a>12548796325845125</a>';
var json = xml2json.parser(xml);
console.log(json); // {a: 12548796325845120}