Merge pull request #223 from Sharpie/vox-build-podman-compat

Add Podman compatibility to vox:build task

Author: nmburgan

rakelib/utils/docker_runner.rb

@@ -16,7 +16,7 @@ def image_exists?
     end
 
     def container_exists?
-      !`docker container ls --all --filter 'name=#{container_name}' --format json`.strip.empty?
+      !`docker container ls --all --filter 'name=#{container_name}' --format '{{json .ID}}'`.strip.empty?
     end
 
     def teardown