Added health check API for the image service (#84)

*Description of changes:*
Added health check API for the image service similar to the vehicle
service.

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sample-applications/vehicle-dealership-sample-app/ImageServiceApp/MainService/urls.py

@@ -8,4 +8,5 @@
     path("", views.index, name="index"),
     path("name/<str:image_name>", views.handle_image, name="image"),
     path("remote-image", views.get_remote_image, name="remote-image"),
+    path("health-check/", views.health_check, name="health_check"),
 ]

sample-applications/vehicle-dealership-sample-app/ImageServiceApp/MainService/views.py

@@ -44,6 +44,10 @@ def index(request):
     return HttpResponse("Hello, world LOL!")
 
 
+def health_check(request):
+    return HttpResponse("Image Service is up and running!")
+
+
 @csrf_exempt
 def handle_image(request, image_name):
     print(image_name)

sample-applications/vehicle-dealership-sample-app/README.md

@@ -143,4 +143,5 @@ The following are the APIs and what they do:
 16. `POST /images/name/<image_name>`: creates an empty file in S3. This is an async endpoint since it will put image 
    name in an SQS queue and not wait for the file to be created in S3. Instead, a long running thread will poll SQS 
    and then create the image file later. 
-17. `GET /image/remote-image`: makes a remote http call to google.com. 
+17. `GET /image/remote-image`: makes a remote http call to google.com. 
+18. `GET /image/heatlh-check/`: returns 200 if the image service is up and running.