[WIP] Skip loading the docker image, when no cookbooks are modified.

Skip loading the docker image,
when no cookbooks are modified.

If no cookbooks are modified,
the docker container will not be used.
[WIP] Skip building the docker image, when no cookbooks are modified.

Skip building the docker images,
when no cookbooks are modified.

This is because When no cookbooks are modified,
the docker images are not used.
Skip building the docker images, when no cookbooks are modified.

Skip building the docker images,
when no cookbooks are modified.

This is because when no cookbooks are modified,
the docker images are no longer used.
Merge pull request #149 from kazu634/build-image-add-condition

Skip building the docker image, when no cookbooks are modified.