very simple write repeater, when gets error, try repeat after 500ms, but max 5 times
@param {String} filePath
@param {String} data to write to file
@param {Function} callback(err)
function writeFile(filePath, data, callback, count){ // callback(err)
    if(typeof callback !== 'function') throw new Error('Wrong arguments');
    filePath = path.resolve(filePath);
    
    count = count || 0;
    var maxLimit = 5; // 5 * 500ms = 2,5s
    
    fs.writeFile(filePath, data, function(err) {
        if(err) {
            if(count >= maxLimit) callback(new Error('fsExt.writeFile: max repeat limit reached').cause(err)); // repeat limit reached
            else setTimeout(function(){
                writeFile(filePath, data, callback, count + 1);
            }, 500);
        }
        else callback();
    });
}