Remove linux specific calls

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume.charmes@docker.com> (github: creack)
Add Freebsd client support

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume.charmes@docker.com> (github: creack)
Create directories for tar files with relaxed permissions

Docker-DCO-1.1-Signed-off-by: Alexey Kotlyarov <alexey@infoxchange.net.au> (github: koterpillar)
Clarify how to update the docs branch in the RELEASE-CHECKLIST with concrete instructions

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Merge branch 'master' into add_freebsd_support

Conflicts:
	archive/archive.go
	archive/start_unsupported.go
Update vendor for kr/pty

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume.charmes@docker.com> (github: creack)
Update bsd specs

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume.charmes@docker.com> (github: creack)
Update vendor.sh with new kr/pty revision

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume@charmes.net> (github: creack)
Merge pull request #3985 from creack/add_freebsd_support

Add freebsd client support
Merge pull request #4440 from infoxchange/aufs-permissions-4068

Create directories for tar files with relaxed permissions
Merge pull request #4564 from vieux/remove_unused_version

Remove unused version.go
nsinit: prefix errors with their source

Docker-DCO-1.1-Signed-off-by: Sridhar Ratnakumar <github@srid.name> (github: srid)
Merge auth package within registry

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume@charmes.net> (github: creack)
Merge pull request #4566 from srid/nsinit_uniq_errors

nsinit: prefix errors with their source
Move signal to pkg

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume@charmes.net> (github: creack)
Create portable signalMap

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume@charmes.net> (github: creack)
Make docker use the signal pkg with strings

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume@charmes.net> (github: creack)
Merge pull request #4515 from vieux/improve_sort_flags

improve alpha sort in mflag
Merge pull request #4567 from creack/merge_auth_registry

Merge auth package within registry
Merge pull request #4520 from tianon/clarify-docs-branch-update

Clarify how to update the docs branch in the RELEASE-CHECKLIST with concrete instructions