Fixed logging out, added a proper function to list sessions

By fixing logging out, other request probably got fixed as well,
since now we can also read MessagesAcknowledge requests

telethon/telegram_client.py

@@ -1,7 +1,7 @@
 import platform
 from datetime import datetime
 from hashlib import md5
-from os import path
+from os import path, listdir
 from mimetypes import guess_extension, guess_type
 
 # For sending and receiving requests
@@ -35,7 +35,7 @@ from telethon.tl.all_tlobjects import layer
 class TelegramClient:
 
     # Current TelegramClient version
-    __version__ = '0.5'
+    __version__ = '0.6'
 
     # region Initialization
 
@@ -182,8 +182,7 @@ class TelegramClient:
     def log_out(self):
         """Logs out and deletes the current session. Returns True if everything went OK"""
         try:
-            # This request is a bit special. Nothing is received after
-            self.sender.send(LogOutRequest())
+            self.invoke(LogOutRequest())
             if not self.session.delete():
                 return False
 
@@ -191,6 +190,13 @@ class TelegramClient:
         except:
             return False
 
+    @staticmethod
+    def list_sessions():
+        """Lists all the sessions of the users who have ever connected
+           using this client and never logged out"""
+        return [path.splitext(path.basename(f))[0]  # splitext = split ext (not spli text!)
+                for f in listdir('.') if f.endswith('.session')]
+
     # endregion
 
     # region Dialogs ("chats") requests