Log Failed Videos

[prof-m]

This commit implements the following:

• The feature request from issue #15 is now functional. To support it, a new CLI argument, --failed-videos-page, has been added to specify the page name. The page must already exist within the Hydrus client at the time the program is run, and it must be a file search page. If there is more than one page with the same name, one of the pages will be chosen pseudo-randomly. If no valid page can be found, it fails gracefully while allowing the program to continue.
• Additionally, all phashing failures with video-specific information are now simultaneously logged to a .txt file for easier info collection (file stored in the same directory as the database files)
• The --job-count parameter can now be set via environment variable
• An additional comment has been added with a specific link for checking the status of 'unordered-generator' on joblib's GH

[prof-m]

Closing this out as you've got it in there! 🎉