use mobileclient.set_user_data() whenever needed/possible

src/c3nav/site/middleware.py

@@ -0,0 +1,10 @@
+class MobileclientMiddleware:
+    """
+    This middleware adds request.mobileclient
+    """
+    def __init__(self, get_response):
+        self.get_response = get_response
+
+    def __call__(self, request):
+        request.mobileclient = 'c3navclient' in request.META['HTTP_USER_AGENT']
+        return self.get_response(request)