Switch handling server urls to static json data in /conference-data/

[sippsack]

The DukeCon Server will not deliver conference data (javalandxxx.json) anymore in a very near future. Instead, single Java processes will import conference data and write it to static files:

https://latest.dukecon.org/conference-data/javaland2016.json
https://latest.dukecon.org/conference-data/javaland2016/speakers/xxx.jpg

The DukeCon PWA client has to read these static files, using If-None-Match (etag) header to avoid unnecessary reads.

[sippsack]

6d07f65

[ahus1]

When you change URLs, please add this to the docs (INTERFACES.adoc).

Also update the service worker configuration to make them available offline (webpack.prod.conf.js, approx. line 127)

[sippsack]

@ahus1 thanks for the remind, will do that.

I still try to figure out the current etag support. Currently it looks like if-none-match also works automatically for conference json data when the service worker fetches data from network. I have to check, if etag support also works for static json files.

[ascheman]

Please check if this issue/branch is still necessary @sippsack, since we try to keep usage of the current interface of DukeCon-Server even with the static data generator (cf. dukecon/dukecon_server#102).