Load a config file instead of hard-coding

[Raduh]

Currently, the IPs as well as some fields (e.g. hit title) are hard-coded.
This is inconvenient when deploying multiple configurations, since one has to keep track of everything that differs and modify the code in a number of places.
They should be in a config file (e.g. arxiv.config, zb.config) which is automatically loaded.

[tkw1536]

@Raduh Isn't https://github.com/KWARC/mws-frontend/blob/master/js/config.js enough to configure?

[Raduh]

Well, should be, but see [1] for example. Some of the last 10 commits or so add deployment specific strings inside the code.

[1] https://github.com/KWARC/mws-frontend/blob/master/js/gui.js#L579