Remove simpleauth

Simple Auth used to provide auth over HTTP. The original motivation
behind this was this was a simple way to add Cloudron Auth integration.
Back in the day, Cloudron Auth was a requirement for apps but this is
not the case anymore.

This is currently not used by any app and having this might encourage
people to make Cloudron specific un-upstreamable changes.

src/routes/oauth2.js

@@ -233,7 +233,6 @@ function loginForm(req, res) {
         switch (result.type) {
             case clients.TYPE_BUILT_IN: return renderBuiltIn();
             case clients.TYPE_EXTERNAL: return render(result.appId, '/api/v1/cloudron/avatar');
-            case clients.TYPE_SIMPLE_AUTH: return sendError(req, res, 'Unknown OAuth client');
             default: break;
         }
 
@@ -450,8 +449,6 @@ var authorization = [
         if (type === clients.TYPE_EXTERNAL || type === clients.TYPE_BUILT_IN) {
             eventlog.add(eventlog.ACTION_USER_LOGIN, auditSource(req, req.oauth2.client.appId), { userId: req.oauth2.user.id });
             return next();
-        } else if (type === clients.TYPE_SIMPLE_AUTH) {
-            return sendError(req, res, 'Unknown OAuth client.');
         }
 
         appdb.get(req.oauth2.client.appId, function (error, appObject) {