CSV export for participants favored lectures

[PhilippMStahn]

Build a query via REST that will immediately publish the title of the lecture and the number of favorites for a specific conference.

[sippsack]

did a first draft. it is deployed at latest, but can't not be tested yet. We need to adapt reverse proxy routes to reach the new endpoint:

https://latest.dukecon.org/javaland/2019/rest/admin/javaland2019/favorites

At the moment only json documents will be returned, I will extend it to CSV output later.

[sippsack]

moved rest endpoint address to rest/favorites/conferenceId (unsecured)

e.g.
http://programm.javaland.eu/2019/rest/favorites/javaland2019
http://programm.doag.org/apex/2019/rest/favorites/apex2019

return CSV (import in Excel as UTF-8!) or JSON (Accept-Header = application/json)