Fix registry pushing/tagging

* docker push host:port/namespace/repo wouldn't push multiple tags for
  the same image
* getImageList was unnecessarily complex returning a nested array of
  ImgData when a correctly ordered list of images was sufficient
* removed various bits of redundancy

Docker-DCO-1.0-Signed-off-by: Danny Yates <danny@codeaholics.org> (github: codeaholics)
Remove unneeded DependencyGraph

Docker-DCO-1.0-Signed-off-by: Danny Yates <danny@codeaholics.org> (github: codeaholics)
Further simplification

Docker-DCO-1.0-Signed-off-by: Danny Yates <danny@codeaholics.org> (github: codeaholics)
Fix indentation to match rest of file (tabs, not spaces)

Docker-DCO-1.0-Signed-off-by: Danny Yates <danny@codeaholics.org> (github: codeaholics)
gofmt

Docker-DCO-1.0-Signed-off-by: Danny Yates <danny@codeaholics.org> (github: codeaholics)
Fix docs manpage generation

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Add Dockerfile man page generation from our Dockerfile reference page

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Update Travis to also compile the man page(s) now that they compile properly again

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Extract cgroups pkg.

Initial move before enhancing cgroups package.

Docker-DCO-1.1-Signed-off-by: Paul Nasrat <pnasrat@gmail.com> (github: pnasrat)
Merge branch 'fix-registry-push-tags' of https://github.com/codeaholics/docker into codeaholics-fix-registry-push-tags

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Fix Travis build errors by bumping our python module versions to be newer

See also https://bitbucket.org/birkenfeld/sphinx/issue/1281/sphinx-113-not-build-proper-manpages

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Make sure new repositories can be pushed with multiple tags

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Merge pull request #3650 from tianon/fix-doc-man-generation

Fix docs man page generation and add Dockerfile man page
Merge pull request #3681 from pnasrat/extract-cgroups-pkg

Extract cgroups into pkg sub dir
Merge pull request #3684 from crosbymichael/push-multiple-tags

Push multiple tags for repository
Fix support for registry auth with Dockerfile build.

Docker-DCO-1.1-Signed-off-by: Jake Moshenko <jake@devtable.com> (github: jakedt)