Fix failing py3 builds attempt 3

Author: pevdh

telebot/apihelper.py

@@ -3,7 +3,8 @@
 import requests
 import six
 import types
-import util
+
+from telebot import util
 from util import logger
 
 API_URL = "https://api.telegram.org/bot{0}/{1}"

telebot/telebot_class.py

@@ -4,9 +4,9 @@
 import re
 import six
 
-import apihelper
-import util
-from util import logger
+from telebot import apihelper
+from telebot import util
+from telebot import logger
 
 
 class TeleBot(apihelper.TelegramApiInterface):

telebot/types.py

@@ -3,7 +3,7 @@
 import json
 import six
 
-import util
+from telebot import util
 
 
 class JsonSerializable: