Added posts and categories

category.model.js

@@ -0,0 +1,16 @@
+const mongoose = require('mongoose');
+const Schema = mongoose.Schema;
+
+// Database schema for an email message
+let Category = new Schema({
+    name: {
+        type: String
+    },
+    color: {
+        type: String
+    },
+}, {
+    collection: 'categories'
+});
+
+module.exports = mongoose.model('Category', Category);