Get an extra pair of eyes on the Softlayer installation docs

Docker-DCO-1.1-Signed-off-by: SvenDowideit <SvenDowideit@home.org.au> (github: SvenDowideit)
Removed docker_io_oauth_api.md: Docker is not currently accepting registrations for third party auth while it's determined how this will be done, if at all, in the future.

Docker-DCO-1.1-Signed-off-by: hollietealok <hollie@docker.com> (github: hollietealok)
Merge remote-tracking branch 'upstream/master' into doc_remove

Docker-DCO-1.1-Signed-off-by: hollietealok <hollie@docker.com> (github: hollietealok)
Standardize "apt-get install" usage across the repo

I might have missed some, but I think this is most of the offenders.

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Removed OAuth doc from mkdocs.yml

Docker-DCO-1.1-Signed-off-by: hollietealok <hollie@docker.com> (github: hollietealok)
utils/tarsum* -> pkg/tarsum

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
move testdata to tarsum package.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Docs: articles/https minor amendments and update

This commit proposes some minor amendments and updates
for the articles/https.md document to fix certain errors, inc.:

 - Marking commands / flags as code (e.g. `tlsverify`) [done before rebase]
 - Capitalising the word Docker
 - Normalizing headers to match the rest of the docs;
 - Expanding the page description to match the page title and the content;
 - Capitalizing HTTPS etc.;
 - Some spelling error fixes;
 - Line-length adjustments to make it easier to read the raw file.

It does not propose any fundemental changes to the structure of the document.
Certain changes were based before another update on this doc.

Docker-DCO-1.1-Signed-off-by: O.S. Tezer <ostezer@gmail.com> (github: ostezer)
utils.Debugf -> fmt.Printf

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Added GA universal analytics support

Docker-DCO-1.1-Signed-off-by: Roberto Hashioka <roberto.hashioka@docker.com> (github: rogaha)
docs/google: bump container-vm image version

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: proppy)
Merge pull request #7337 from rogaha/add_ga_universal_analytics_support

Added GA universal analytics support
Bump libcontainer dep

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Add support for autodetected HOME from USER (if HOME is unset)

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Remove pkg/user now that it's embedded in libcontainer

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Update TestEnvironment to explicitly set "HOME" to be empty so it gets autofilled

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Update CONTRIBUTING.md with links to sections and RFE process.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Merge pull request #7193 from hollietealok/doc_remove

Removed docker_io_oauth_api.md: Docker is not currently accepting regist...
Merge pull request #7343 from shykes/cleanup-main

Cleanup main function
Merge pull request #7091 from erikh/rfe

Update CONTRIBUTING.md with links to sections and `Proposal:` process.