resumablerequestreader: allow initial response

Make it possible to inspect an initial response and pass it to
ResumableRequestReader. This makes it possible to inspect an initial
response and passing it to ResumableRequestReader to avoid making an
extra request.

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
get layer: remove HEAD req & pass down response

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
archive: add buffers to operations with tarballs

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
archive: add a benchmark for TarUntar

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
Reorganize and clarify the DOCKER_BUILDTAGS docs

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Add AUDIT_WRITE cap

Fixes #6345

Thanks @larsks for outstanding investigation

Docker-DCO-1.1-Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com> (github: LK4D4)
[DOCS] replace foo/bar with concrete names

namespaces are not well documented, and I had to jump around to other docs. replacing `foo/bar` hopefully makes what's going on here a bit more obvious.

Docker-DCO-1.1-Signed-off-by: Tim Ruffles <timruffles@gmail.com> (github: timruffles)
Merge pull request #6727 from unclejack/improve_bytes_range

Improve layer downloading
Typo changes to docker-run-1.md - changing '-' to '--' where approp.

Docker-DCO-1.1-Signed-off-by: William Henry <whenry@redhat.com> (github: ipbabble)
Merge pull request #7108 from unclejack/archive_speedup

speed up archive
Merge pull request #7181 from timruffles/patch-3

[DOCS] replace foo/bar with concrete names
Merge pull request #7148 from tianon/buildtags-docs

Reorganize and clarify the DOCKER_BUILDTAGS docs
Fix incorrect path in ENTRYPOINT example

The ENTRYPOINT example uses "/usr/bin/ls" as path, but `ls` is located at `/bin/ls`.

Docker-DCO-1.1-Signed-off-by: Sebastiaan van Stijn <github@gone.nl> (github: thaJeztah)
Merge pull request #7199 from ipbabble/mp-changes

Fixed some typos for '--' Vs '-' in docker-run-1.md
Properly handle 0 being passed as a signal

Docker-DCO-1.1-Signed-off-by: Matt Heon <mheon@redhat.com> (github: mheon)
Merge pull request #7179 from LK4D4/add_cap_audit_write_#6345

Add AUDIT_WRITE cap
Merge pull request #7212 from mheon/kill_zero

Properly handle 0 being passed as a signal number
update go import path and libcontainer

Docker-DCO-1.1-Signed-off-by: Victor Vieux <vieux@docker.com> (github: vieux)
gofmt -s -w

Docker-DCO-1.1-Signed-off-by: Victor Vieux <vieux@docker.com> (github: vieux)
revert AUTHORS changes

Docker-DCO-1.1-Signed-off-by: Victor Vieux <vieux@docker.com> (github: vieux)