* Add instagram metadata: post_pageurl, post_tags
Add the following metadata for instagram:
- post_pageurl: json string with url of the post page
- post_tags: json array with instagram tags extracted from the post description
* Oops: rename post_tags to tags for --write-tags
This way, --write-tags will pick up the post tags.
* Rename to post_url, improve regex
* Add post_url and tags to tests
* Remove duplicate tags and sort them
* Bugfix: don't create empty tag lists
* Metadata: add location
* Metadata: add tagged_users for each media
* Move self._find_tags() to base class
* Make flake happy
62b65e59d0