v1.8.0 (#105)

## Change log
  
- Youtube support added
- Custom filenames feature added
- Custom folder structure feature added
- Unsaving downloaded posts option added
- Remove duplicate posts on different subreddits option added
- Skipping given domains option added
- Keeping track of already downloaded posts on a separate file option added (See --dowloaded-posts in README)
- No audio on v.redd.it videos bug fixed (see README for details about ffmpeg)
- --default-directory option is added
- --default-options is added
- --use-local-config option is added
- Bug fixes

requirements.txt

@@ -1,4 +1,5 @@
 bs4
 requests
 praw
-imgurpython
+imgurpython
+youtube-dl