Resolve "Adapt for SPA operations"

Closes #17 (closed)

aleksis/apps/resint/frontend/messages/en.json

 {
-
+  "resint": {
+    "menu_title": "Documents",
+    "manage_posters": {
+      "menu_title": "Manage posters"
+    },
+    "poster_groups": {
+      "menu_title": "Poster groups"
+    },
+    "live_documents": {
+      "menu_title": "Live documents"
+    }
+  }
 }