Introduce account document to user document

An account document is attached to a user document if an account of the
user is on the server. It may be missing if the user is on a remote server.

src/api/endpoints/auth/accept.ts

@@ -45,7 +45,7 @@ module.exports = (params, user) => new Promise(async (res, rej) => {
 
 	// Fetch token
 	const session = await AuthSess
-		.findOne({ token: token });
+		.findOne({ 'account.token': token });
 
 	if (session === null) {
 		return rej('session not found');