Missing Error Handling for Limit equal or less than 0 when executed using from another Python file

[CaioRhoden]

Heyy, I've used this lib for a personal proejct and now I'm using it for a college course on Software Testing, applying some tests I identified the following problem in error handling

Issue description

When the limit argument (optional) is set to zero or below the lib download the 100 default image without any warning or exception
because of the invalid parameter passed

Steps to reproduce the issue

1. Clone repository
**2. **cd google-images-download && sudo python setup.py install
3. In this respository create a python script
4. Import from google_images_download import google_images_download
5. Add the following commands

response = google_images_download.googleimagesdownload() 
arguments = {'keywords': 'dog', 'limit': 0}
response.download(arguments)

6. Run script

What's the expected result?

• Some error message to explicit that is not possible to download 0 images

What's the actual result?

• It downloads all default 100 images

Additional details / screenshot