Add crawls_crawlschedule table to 0.8.x test schema and fix migrations

- Add missing crawls_crawlschedule table definition to SCHEMA_0_8 in test file
- Record all replaced dev branch migrations (0023-0074) for squashed migration
- Update 0024_snapshot_crawl migration to depend on squashed machine migration
- Remove 'extractor' field references from crawls admin
- All 45 migration tests now pass (0.4.x, 0.7.x, 0.8.x, fresh install)

archivebox/core/migrations/0024_snapshot_crawl.py

@@ -10,7 +10,7 @@ class Migration(migrations.Migration):
     dependencies = [
         ('core', '0023_new_schema'),
         ('crawls', '0001_initial'),
-        ('machine', '0001_initial'),
+        ('machine', '0001_squashed'),
     ]
 
     operations = [