Implement discovery v2

[jornane]

There are some problems with the old discovery mechanisms, that make some things a bit more complicated than they need to be. Other issues that are easier to solve with a new discovery can have this issue as a dependency.

This issue is made under the ionic-app project, but design of the discovery

Features we want for the new discovery:

• Smaller initial discovery, only institutions are listed
• Language support
• Institution can be represented by a single URL, not three as it is now for OAuth flow (Use custom URL ionic-app#8)
• Easy enrollment via CAT redirect URL (scraper can get enough info by following the redirect URL)
• Institution keywords so that a user can write "NTNU" instead of "Norges Teknisk-Naturvitenskaplige Universitet"
  • CAT has no support for this, how to solve?

Maybe nice to have

• Signing so that we can host the discovery wherever (Amazon?)
• Another format than JSON to reduce size even more (msgpack?)
• Logo in discovery, CAT already provides this
  • Logo URL both in the discovery file and the institution file?
• Helpdesk info in the institution config, CAT only provides helpdesk info per profile

Proposal thus far:

• Supported languages can be retrieved from https://discovery.geteduroam.no/v2/language.json
• English (en) is always supported, so if that is the preferred language, the language.json endpoint does not have to be used
• The discovery file is available at /v2/$LANG/discovery.json, e.g. https://discovery.geteduroam.no/v2/en/discovery.json
• The discovery file points to another file per institution. This can be a file in the same directory as the discovery, or a whole new URL
  • The app must support for inputting this URL directly, as an advanced option (solution for Use custom URL ionic-app#8)