Signed-off-by: Adam Reese <adam@reese.io>

Docker stopped releasing binaries to get.docker.com as of 17.03.0-ce. They are all hosted at download.docker.com now.

I also had to downgrade docker to 17.09.0-ce because that's the only version that both download.docker.com and
CircleCI support.

https://download.docker.com/linux/static/stable/x86_64/
https://circleci.com/docs/2.0/building-docker-images/#docker-version

This commit does a few things:
* It moves the information being cached to be the glide cache.
  This will make the glide install process faster.
* The cache is restored from prior to installing the dependencies.

CircleCI recently skipped building tags by default, so we need to
explicitly enable it.

See https://circleci.com/docs/2.0/configuration-reference/#tags

https://circleci.com/docs/2.0/configuration-reference/#deploy