Show list of supported client applications

[nichtich]

In addition to #70 show supported client applications without active session and assign names to active sessions. This requires an additional config file applications.json:

[
  { "url": "//bartoc.org/", "name": "BARTOC" },
  { "url": "//coli-conc.gbv.de/cocoda/", "name": "Cocoda" },
  { "url": "//coli-conc.gbv.de/coli-rich/", "name": "coli-rich" }
]

Some sessions can be mapped to applications to show their name instead of the URL.

[stefandesu]

If we add an applications.json file, we have two options:

1. Either we don't commit it into the repo, thus every instance needs to provide its own file,
2. or we do commit it, but there's no easy way of adding additional applications.

I tend towards 1. In theory, we could have a default set of applications (either hardcoded or in a applications.default.json). What do you think?

[nichtich]

ALLOWED_ORIGINS has no default value neither, so

3. The list of applications is empty if no applications.json exists.

[stefandesu]

The list of applications is empty if no applications.json exists.

So 1. 😉 The default set was just a thought and basically my number 3.