Added functionality to search for Facebook groups

[bipsen]

We spoke previously about adding functionality for searching for Facebook groups. Here, I've added that functionality to the FacebookScraper class, and added a function in init to use it directly.

Here is how it works:

from facebook_scraper import get_groups_by_search

for group_info in get_groups_by_search('golf', cookies='cookies.json'):
    print(group_info)

[neon-ninja]

Thanks for your contribution!