Activate response compression in application.yml

[datazuul]

compression of responses (e.g. json of manifest) reduces traffic. in cases where a webserver is in front of hymir, compression should be done there. nonetheless compression reduces cache storage if webserver caches responses from application (e.g. with nginx in front of hymir)

see https://docs.spring.io/spring-boot/docs/current/reference/html/common-application-properties.html

server.compression.enabled=false # Whether response compression is enabled.
server.compression.excluded-user-agents= # Comma-separated list of user agents for which responses should not be compressed.
server.compression.mime-types=text/html,text/xml,text/plain,text/css,text/javascript,application/javascript,application/json,application/xml # Comma-separated list of MIME types that should be compressed.
server.compression.min-response-size=2KB # Minimum "Content-Length" value that is required for compression to be performed.