Fix aggressive prune breaking rollback

In the image prune command --all overrides --dangling=true. This removes
the image git sha image tag for the latest image which prevented
us from rolling back to it.

I've updated the integration test to now test deploy, redeploy and
rollback.

test/cli/prune_test.rb

@@ -10,7 +10,7 @@ class CliPruneTest < CliTestCase
 
   test "images" do
     run_command("images").tap do |output|
-      assert_match /docker image prune --all --force --filter label=service=app --filter dangling=true on 1.1.1.\d/, output
+      assert_match /docker image prune --force --filter label=service=app --filter dangling=true on 1.1.1.\d/, output
     end
   end