This PR adds functionality to crawl the CC-NEWS dataset.

The file structure shadows the structure used in the main scraping directory. This code is currently mostly separated from the main files because those still use asyncio and thus are incompatible. When the main crawler gets rewritten, the code should be merged (not speaking about the PR).

Here is a quick tutorial on how to use the crawler.

Basic usage:

from fundus import CCNewsCrawler, PublisherCollection

crawler = CCNewsCrawler(*PublisherCollection)
for article in crawler.crawl(max_articles=100):
    print(article)

With date range:

from fundus import CCNewsCrawler, PublisherCollection
from datetime import datetime

crawler = CCNewsCrawler(*PublisherCollection)
for article in crawler.crawl(start=datetime(2020, 1, 1), end=datetime(2020, 3, 1), max_articles=20000):
    print(article)

Using the above block of code, I was able to crawl 20000 articles in 1:35 minutes on a machine with 10 GB bandwidth and 72 cores.

closes #44
closes #45