Resolve "TypeError at /celery_progress/.../ 'AnonymousUser' object is not iterable"

Closes #498

See merge request !703

Resolve "Allow apps to register OAuth scopes"

Closes #495

See merge request !698

Update changelog from 2.0rc4

See merge request !700

(cherry picked from commit 7f22f081)

This replaces the settings merging for the static
`OAUTH2_PROVIDER["SCOPES"]` setting.

Attention: Breaking change, only release with next major version. Can
be backported to minor release if support for old mechanism is glued
into the new one, with a deprecation warning.

Resolve "Error in 5xx pages"

Closes #494

See merge request !696

Merge branch '494-error-in-5xx-pages' of edugit.org:AlekSIS/official/AlekSIS-Core into 494-error-in-5xx-pages

Resolve "serviceworker.js delievered as binary chunks"

Closes #493

See merge request !695

Resolve "Improve rule-checking efficiency"

Closes #491

See merge request !694

Resolve "[Monitoring] Allow to configure metrics port"

Closes #490

See merge request !692

Update changelog from 2.0rc3

See merge request !693

(cherry picked from commit 8f3d9750)

Resolve "Fix search.js autocompletion"

Closes #488

See merge request !688

Update missing changelog

See merge request !690

Support PDF generation without available request object

See merge request !689