Fix docker auth with pillar

Authentication to docker daemon using pillar was also broken (related to #13305).
I fixed only the support of `~/.dockercfg` in 
https://github.com/saltstack/salt/commit/1b3fc8de258e6f81e6319056231e3263d35ff152
<strike>It might be also good to backport it to 2014.1</strike>