Add a 'view' parameter for all entity endpoints

See merge request !128

A JsonView for serialization is applied based on the 'view' query
parameter.

The following values are currently supported:
* admin (View.Admin.class)
* owner (View.Owner.class)
* <unset> (Public.Admin.class)

Return 403 Forbidden on duplicated username when registering

Closes #38

See merge request arsnova/arsnova-backend!126

The RegEx unintentionally required a minimum length of 2 for IDs.

Enable rabbitmq

See merge request arsnova/arsnova-backend!122

add queue naming conventions to doc

add management interface into to rabbit file

Add auth logic for stomp clients over ws

See merge request arsnova/arsnova-backend!123

Tom Käsler authored 5 years ago and Daniel Gerhardt committed 5 years ago

remove unneccessary imports
use correct Nullable from checkerframework

Fix feedback messaging

See merge request arsnova/arsnova-backend!121

The version set for Pac4j was previously ineffective because it was set
by spring-security-pac4j first.

The Spring Platform BOM has reached EOL, so we need to replace it for
future updates. This should not change any dependency versions.

https://spring.io/blog/2018/04/09/spring-io-platform-end-of-life-announcement

See GH-65.

Add websocket handler to component scan

See merge request !119

add WebSockets with STOMP on top

See merge request !112

remove unused imports

move ws handler to websocket package

add WebSocketMessage entity structure
add basic feedback logic
add tests for Feedback messages

These tests exercise the happy path. If needed, negative tests could
be added in the future.

Ektorp's default implementation expects purge_seq to be of type int.
CouchDB 2.x purge_seq is of type String.

Reverts 8ad7cd84

This fixes issue #33. However, it is still unclear why different
beans are shared between test and production code.