Add Content-Type header in PushImageLayerRegistry

Docker-DCO-1.1-Signed-off-by: Gabor Nagy <mail@aigeruth.hu> (github: Aigeruth)
Added :neckbeard: RMS the founder of :water_buffalo: GNU and :free: as in :free:dom software

Docker-DCO-1.1-Signed-off-by: Aleksandrs Fadins <aleks@s-ko.net> (github: muchweb)
Removed :neckbeard: RMS test case

Docker-DCO-1.1-Signed-off-by: Aleksandrs Fadins <aleks@s-ko.net> (github: muchweb)
contrib/init/systemd: add philips as MAINTAINER

As requested after #7021 add me as a maintainer alongside the sword
toting @lsm5.

Docker-DCO-1.1-Signed-off-by: Brandon Philips <brandon.philips@coreos.com> (github: philips)
Give context for the error that occures when you try to bind mount a volume with a relative path

Docker-DCO-1.1-Signed-off-by: Timothy <timothyhobbs@seznam.cz> (github: timthelion)
Update dockerlinks.md

Added missing command for logging into web container.
Move TestCopyVolumeUidGid to integration-cli

Docker-DCO-1.1-Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com> (github: LK4D4)
Move TestCopyVolumeContent to integration-cli

Docker-DCO-1.1-Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com> (github: LK4D4)
Adjust Travis to also compile, to test that compilation still succeeds

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Merge pull request #7117 from hipertracker/patch-1

Update dockerlinks.md
Fix minor grammar issues in dockervolumes.md
Merge pull request #7131 from msabramo/patch-1

Fix minor grammar issues in dockervolumes.md
Merge pull request #7116 from timthelion/relativevolumeerror

Give context for the error that occures when you try to bind mount a vol...
Merge pull request #7124 from tianon/travis-compile

Adjust Travis to also compile, to test that compilation still succeeds
Merge pull request #7122 from LK4D4/move_some_run_tests_to_cli

Move some run tests to cli
Merge pull request #7090 from philips/add-philips-to-systemd-maintainers

contrib/init/systemd: add philips as MAINTAINER
Merge pull request #7061 from muchweb/rms

Can't believe you forgot RMS
Merge pull request #7050 from Aigeruth/fix/push_image_layer_registry_content_type

Add Content-Type header in PushImageLayerRegistry