Separate start_webhook and setWebhook

I think starting and setting the webhook should be two different tasks.
Because the internal webhook and the adress you see from outside can be
quite diffrent through apache etc. It provides more flexibility.

telegram/updater.py

@@ -11,7 +11,6 @@ from threading import Thread
 from time import sleep
 import subprocess
 from signal import signal, SIGINT, SIGTERM, SIGABRT
-
 from telegram import (Bot, TelegramError, dispatcher, Dispatcher,
                       NullHandler)
 from telegram.utils.webhookhandler import (WebhookServer, WebhookHandler)
@@ -92,17 +91,17 @@ class Updater:
         # Return the update queue so the main thread can insert updates
         return self.update_queue
 
-    def start_webhook(self, host, port, listen='0.0.0.0', cert=None, key=None):
+    def start_webhook(self, listen='127.0.0.1', port=80, url_path='', cert=None, key=None):
         """
         Starts a small http server to listen for updates via webhook. If cert
         and key are not provided, the webhook will be started directly on
-        http://host:port/, so SSL can be handled by another application. Else,
-        the webhook will be started on https://host:port/<bot_token>
+        http://listen:port/url_path, so SSL can be handled by another application. Else,
+        the webhook will be started on https://listen:port/url_path
 
         Args:
-            host (str): Hostname or IP of the bot
-            port (int): Port the bot should be listening on
             listen (Optional[str]): IP-Address to listen on
+            port (Optional[int]): Port the bot should be listening on
+            url_path (Optional[str]): Path inside url
             cert (Optional[str]): Path to the SSL certificate file
             key (Optional[str]): Path to the SSL key file
 
@@ -115,7 +114,7 @@ class Updater:
                                    name="dispatcher")
         event_handler_thread = Thread(target=self._start_webhook,
                                       name="updater",
-                                      args=(host, port, listen, cert, key))
+                                      args=(listen, port, url_path, cert, key))
 
         self.running = True
 
@@ -170,24 +169,10 @@ class Updater:
 
         self.logger.info('Updater thread stopped')
 
-    def _start_webhook(self, host, port, listen, cert, key):
+    def _start_webhook(self, listen, port, url_path, cert, key):
         self.logger.info('Updater thread started')
         use_ssl = cert is not None and key is not None
-
-        url_base = "https://%s:%d" % (host, port)
-        if use_ssl:
-            url_path = "/%s" % self.bot.token
-            certfile = open(cert, 'rb')
-        else:
-            url_path = "/"
-            certfile = None
-
-        # Remove webhook
-        self.bot.setWebhook(webhook_url=None)
-
-        # Set webhook
-        self.bot.setWebhook(webhook_url=url_base + url_path,
-                            certificate=certfile)
+        url_path = "/%s" % url_path
 
         # Create and start server
         self.httpd = WebhookServer((listen, port), WebhookHandler,