[WIP] Host evidence uploaded to openbadger via "issue with evidence"

[ghost]

This PR makes openbadger hold on to the evidence uploaded via the "Issue One With Evidence" functionality, rather than destroying the evidence once the badge is claimed. It also adds an evidence display page which can be found at /badge/evidence/

Note that there isn't currently any natural way to navigate to this new evidence display page, nor is the page itself particularly attractive. I was worried about displaying any user information on the page, so it doesn't have any indication as to whose badge you are looking at, which makes it feel a little weird. Currently this page requires no authentication, simply because I wasn't sure how private evidence is supposed to be. Should it be admin-only?

I welcome any comments, as I'm not especially happy with this implementation, and regard it as a very rough first pass.

[carlacasilli]

Hey Erik,

Lots of good questions.

Viewing evidence once public
As for who should be able to view evidence once the badge is public, generally this should be anyone who has access to the badge.

Reference info
And I'd say that it should contain reference information as to which badge it's associated with, otherwise it might make gaming the system quite simple.

Access to publishing
Regarding who has access to the page, I'm wondering if you mean from the issuer side, and if so, most likely it makes sense that only the issuing body would have this access.

Is it possible to see what the page looks like so we can review?

Thx! ✌️

[threeqube]

Yeah would definitely like to check it out too to have a visual reference.