move middleware.locals only where it is needed and transform it into a common function, simplify translations and adds automatic language detection

src/server.js

@@ -94,7 +94,6 @@ app.use(express.cookieParser());
 app.use(express.cookieSession({ secret: nconf.get('SESSION_SECRET'), httpOnly: false, cookie: { maxAge: TWO_WEEKS }}));
 //app.use(express.session());
 app.use(middleware.splash);
-app.use(middleware.locals);
 
 // Initialize Passport!  Also use passport.session() middleware, to support
 // persistent login sessions (recommended).