Create snapshots on web.archive.org for bookmarks (#150)

* Implement initial background tasks concept

* fix property reference

* update requirements.txt

* simplify bookmark null check

* improve web archive url display

* add background tasks test

* add basic supervisor setup

* schedule missing snapshot creation on login

* remove task locks and clear task history before starting background task processor

* batch create snapshots after import

* fix script reference in supervisord.conf

* add option to disable background tasks

* restructure feature overview

bookmarks/services/importer.py

@@ -5,6 +5,7 @@ from django.contrib.auth.models import User
 from django.utils import timezone
 
 from bookmarks.models import Bookmark, parse_tag_string
+from bookmarks.services import tasks
 from bookmarks.services.parser import parse, NetscapeBookmark
 from bookmarks.services.tags import get_or_create_tags
 from bookmarks.utils import parse_timestamp
@@ -38,6 +39,9 @@ def import_netscape_html(html: str, user: User):
             logging.exception('Error importing bookmark: ' + shortened_bookmark_tag_str)
             result.failed = result.failed + 1
 
+    # Create snapshots for newly imported bookmarks
+    tasks.schedule_bookmarks_without_snapshots(user.id)
+
     return result