Make list=novainstance available to anons

Right now, none of this information is available to you unless:

- You are logged in
- You are a member of the project

I talked to Andrew and Coren, and we're all ok with making this
info publicly available - nothing private here, and all of it
is exposed via SMW anyway.

Change-Id: Ia9ed925c1e75fce29baf9a1b81cf2a23b0eb6e0f
Cache instance lists for 1 minute when called via API

- No invalidation, but that's ok. Invalidation is hard
  because not all operations have to go through wikitech.
- This is primarily an anti DDoS measure.

Change-Id: I1b56ba9688315b5b4ca17ad527db5e8f5e9c2393