Squad

* celery: correctly load configuration from Django settings

* settings: take Celery broker URL via environment

* fix crash in admin by removing debug print

* api: add REST API for email templates
* ci/lava:
* don't crash if there is no metadata
* update listener to match new LAVA state machine

* core, api: migrate to Django REST Framework tokens
* The old squad-specific Token model has been migrated to Django REST
Framework tokens. The actual data for the old tokens is still there, but
it's not used for anything anymore. It will be automatically removed in the
next release.
* core:
* add support for test case variants
* frontend:
* return 404 on non-existing data
* add initial user settings UI
* add API token settings page
* improve display of descriptions in project list
* api
* Add CORS support via django-cors-headers
* fix TestSerializer
* make Project.slug readonly
* ci/lava:
* add more strings to automatic resubmit list
* parse LAVA log using incremental parser
* add unit test for log parsing

* admin: allow manually triggering post-processing of test run data
* api: add `filter_fields` to BuildViewSet
* api: add ID field to objects returned by REST API
* api: Add ProjectStatus to REST API
* ci: fetch test result data in chunks in LAVA backend
* ci/lava: restore downloading logs
* frontend: Add pagination to test and metric listings
* frontend: fix environment label in tests history table
* frontend: improvements to the resubmit UI
* frontend: paginate "all test results" page
* scripts: add script to migrate testruns between projects
* Store and display metadata about environments, suites, tests, and metrics