Update release notes for v3.1.0

Add Quay links to ARM repositories

Ensure binary archives are gzipped

feat(arm): Cross build arm and arm64 docker images

Change cookie index separator to underscore

Whitelist domains

Co-Authored-By: marratj <marrat@marrat.de>

- Requires `qemu-user-static`, added to travis - maybe incorrect?
- Add build guide
- `.gitignore` `release/` directory

feat(arm): Makefile add armv6 and arm64 to releases

Returns HTTP unauthorized for ajax requests instead of redirecting to the sign-in page

* Implemented flushing interval

When proxying streaming responses, it would not flush the response writer buffer until some seemingly random point (maybe the number of bytes?). This makes it flush every 1 second by default, but with a configurable interval.

* flushing CHANGELOG

* gofmt and goimports

watcher: properly break out in nested blocks

Found via staticcheck:

watcher.go:48:5: ineffective break statement. Did you mean to break out of the outer loop? (SA4011)

* redirect to original path after login

* tests for new redirect behaviour

* fixed comment

* added redirect fix to changelog

OIDC ID Token, Authorization Headers, Refreshing and Verification