Use imagePullPolicy: Always

This isn't optimal, but right now it's easy to get into problems using
tye because we don't generate manifests with digests.

As an example, if you don't have any versioning in your project, right
now we will *just* tag everything with 1.0.0. This can lead to pods
getting deployed with stale images, even though you pushed!

A better solution is for us to use digests instead of tags.

src/opulence/dotnet-opulence/KubernetesManifestGenerator.cs

@@ -132,6 +132,7 @@ namespace Opulence
                 containers.Add(container);
                 container.Add("name", service.Service.Name); // NOTE: to really support multiple images we'd need to generate unique names.
                 container.Add("image", $"{image.ImageName}:{image.ImageTag}");
+                container.Add("imagePullPolicy", "Always"); // helps avoid problems with development + weak versioning
 
                 if (service.Service.Environment.Count > 0 ||