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/routes/wellknown.js

@@ -4,18 +4,18 @@ exports = module.exports = {
     get
 };
 
-const apps = require('../apps.js'),
+const domains = require('../domains.js'),
     HttpError = require('connect-lastmile').HttpError;
 
 function get(req, res, next) {
     const host = req.headers['host'];
 
-    apps.getByFqdn(host, function (error, app) {
+    domains.get(host, function (error, domain) {
         if (error) return next(new HttpError(404, error.message));
 
         const location = req.params[0];
-        if (!app.wellKnown || !(location in app.wellKnown)) return next(new HttpError(404, 'No custom well-known config'));
+        if (!domain.wellKnown || !(location in domain.wellKnown)) return next(new HttpError(404, 'No custom well-known config'));
 
-        res.status(200).send(app.wellKnown[location]);
+        res.status(200).send(domain.wellKnown[location]);
     });
 }