move wellKnownJson to domains

after some more thought:
* If app moves to another location, user has to remember to move all this config
* It's not really associated with an app. It's to do with the domain info
* We can put some hints in the UI if app is missing.

part of #703

src/test/groups-test.js

@@ -24,7 +24,8 @@ var GROUP1_NAME = 'externs',
 const DOMAIN_0 = {
     domain: 'example.com',
     zoneName: 'example.com',
-    config: { provider: 'manual' }
+    config: { provider: 'manual' },
+    wellKnown: null
 };
 
 var USER_0 = {