Make sure err never gets masked

Defining err as named return parameter will make sure the variable gets
assigned before returning and thus avoid masking

Docker-DCO-1.1-Signed-off-by: Johannes 'fish' Ziemke <github@freigeist.org> (github: discordianfish)
fix docker integration-cli restart test race

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Replace old index image with hub

Docker-DCO-1.1-Signed-off-by: Brian Goff <cpuguy83@gmail.com> (github: cpuguy83)
Make --attach case-insensitive

Docker-DCO-1.1-Signed-off-by: Tibor Vass <teabee89@gmail.com> (github: tiborvass)
Merge pull request #7298 from erikh/fix_cli_restart_test

fix docker integration-cli restart test race
Merge pull request #7100 from discordianfish/fix-port-allocation

Fix masked err in portmapper
Fix more instances of "dotcloud/docker" in hack/ (and add a DOCKER_PKG environment variable to simplify references to our "package path" in our bundlescripts)

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Merge pull request #7325 from tiborvass/case-insensitive-attach

Make --attach case-insensitive
Fix graph/tags_unit_test.go on FreeBSD

- Directories should have u+x (0600 -> 0700)
- Don't chown files to root because we don't have to

Docker-DCO-1.1-Signed-off-by: Kato Kazuyoshi <kato.kazuyoshi@gmail.com> (github: kzys)
Remove perm change in archive
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)
Merge pull request #7340 from crosbymichael/tags-unit

Fix graph tags test on freebsd
Merge pull request #7328 from cpuguy83/fix_search_image_oldindex

Replace old index image with hub
Merge pull request #7338 from tianon/moar-dotcloud

Fix more instances of "dotcloud/docker" in hack/
builder/builder.go: Remove 'errors' requirement and dependencies in
favor of fmt.Errorf

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
remove the never-used BuildFile interface and capitalize the buildFile
struct so it can be referenced.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
builder: split builder.go into 3 files, commands and command_support are
for dockerfile commands

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
builder: public interfaces/structs first in the file, privates below

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