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/database-test.js

@@ -85,7 +85,8 @@ const DOMAIN_0 = {
     zoneName: 'foobar.com',
     provider: 'digitalocean',
     config: { token: 'abcd' },
-    tlsConfig: { provider: 'fallback' }
+    tlsConfig: { provider: 'fallback' },
+    wellKnown: null
 };
 
 const DOMAIN_1 = {
@@ -93,7 +94,8 @@ const DOMAIN_1 = {
     zoneName: 'cloudron.io',
     provider: 'manual',
     config: null,
-    tlsConfig: { provider: 'fallback' }
+    tlsConfig: { provider: 'fallback' },
+    wellKnown: null
 };
 
 describe('database', function () {