Merge pull request #253 from MBoretto/fixemptyname

fix user empty name

See discussion here: #250 

src/Entities/User.php

@@ -34,9 +34,6 @@ class User extends Entity
         }
 
         $this->first_name = isset($data['first_name']) ? $data['first_name'] : null;
-        if (empty($this->first_name)) {
-            throw new TelegramException('first_name is empty!');
-        }
 
         $this->last_name = isset($data['last_name']) ? $data['last_name'] : null;
         $this->username = isset($data['username']) ? $data['username'] : null;