Add some cache for the large overlay code

closed #9

overlay/views.py

 from django.shortcuts import render, get_object_or_404
 from django.core.exceptions import PermissionDenied
 from django.views.decorators.csrf import csrf_exempt
+from django.views.decorators.cache import cache_control
 from django.core.mail import EmailMessage
 from django.template import *
 from django.template import loader
@@ -9,7 +10,9 @@ from projector.models import Project
 from urllib.parse import urlparse
 import json
 
+
 # Create your views here.
+@cache_control(max_age=3600)
 def overlay_bundle(request, pk):
     
     context = {