Download history database

[rgathub]

Description

This PR adds option to enable a sqlite database for all downloads using hash to avoid downloading the same file again.
It also fixes the latest oAuth issue with latest version of PRAW.

Changes

• Fixes oAuth issue with latest version of oAuth.
• Adds flags "enable_downloads_db" and "downloads_db_name" to create a sqlite database that stores records of downloaded files to avoid duplicate downloads in future.
• Removed gyfcat as it does not exists from tests.
• Updated test resources as some no longer exists or have updated hashes.

Existing Issues

• Imgur support is out dated and is not working.

[Serene-Arc]

Hi! Thanks for the PR. I've been meaning to go through and fix all the tests and start merging PRs again, but to be honest, I haven't been wanting to go through a bunch of porn to get all the scrapers working. Thanks for doing that for me.

This is mostly fine. I have made some notes, and if there are new options being added to the CLI, then they need to be added to the README as well.

[Serene-Arc]

If you look at the comments, these are two different types of resource. The tests must be replaced with similar ones to make sure that they don't start failing for different types of web pages. You replaced a video with a video, but there needs to be an image album as well.