Fix for saving image in database

Because of following changes in ```file.py``` of previous commit :
 - ```if img_type == "" or img_type == None:```

Image without tags was giving following error :
 - ```Some Exception: <imagename>.jpg Execption: 'NoneType' object has no attribute 'split'```

This is fixed now by : 
 - Changing ```tags = request.POST.get('tags')``` --to-->  ```tags = request.POST.get('tags', "")```