PR for factories

Since we are using `CommentFactory` from `factories.py` in production, I made sure that it returns random correct data. Tests are all passing.
In https://github.com/NiGhTTraX/hackernews-scraper/blob/master/hackernews_scraper/test/test_scraper.py#L22 we test scraping comments that are older than `42`. This sequence could, eventually, return something smaller than 42. Highly unlikely, but the code is ambiguous. You should update the tests to explicitly override the `created_at_i` attribute. Do a `grep since` in the test folder to find all occurrences.