code: function commonUserName(objs, logger){
    logger.info('finding common username');
    var i = objs.length,
        x = 0
        usernames = [],
        highest = 0, 
        out ='';
  
    while (x < i) {
        appendName(objs[x].userName);
        x++;
    }
  
    var i = usernames.length;
    while (i--) {
      if(usernames[i].count > highest){
        highest = usernames[i].count;
        out = usernames[i].name;
      }
    }
  
    function appendName(userName){
      var i = usernames.length;
      while (i--) {
        if(usernames[i].name === userName){
          usernames[i].count ++;
          return;
        }
      }
      usernames.push({
        'name': userName, 
        'count': 1
      })
    }
  
    return out;
  }
docs: find the most common username by freguency of use