Add User json convert.

telebot/types.py

@@ -20,7 +20,23 @@ ReplyKeyboardHide
 ForceReply
 """
 
+import json
+
+
 class User:
+    @classmethod
+    def de_json(cls, json_string):
+        obj = json.loads(json_string)
+        id = obj['id']
+        first_name = obj['first_name']
+        last_name = None
+        username = None
+        if 'last_name' in obj:
+            last_name = obj['last_name']
+        if 'username' in obj:
+            username = obj['username']
+        return User(id, first_name, last_name, username)
+
     def __init__(self, id, first_name, last_name=None, username=None):
         self.id = id
         self.first_name = first_name