fix(CONTRIBUTING): Developer Certificate of Origin w/o Grant

In 7fb55f77250a9b52b0515a7e655ecc605ae452ca the DCO lost the grant so
change the title back to just DCO.

Docker-DCO-1.1-Signed-off-by: Brandon Philips <brandon.philips@coreos.com> (github: philips)
Remove unused reflink files
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Move proxy into pkg
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Move volumes out of container.go and into volumes.go

This helps clean up the container file and move volumes into
one location.  We currently cannot move volumes to a sub pkg
because they depend on Container and also modify fields on the
container.
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Remove container dependency for links
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Move links to sub pkg
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Add socket activation for go apps
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Use socket activation pkg for listeners
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Integration generic socket wait for docker api
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Change name to listenbuffer
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
change the -H TCP / docker group warning to not reference a resolved issue

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au> (github: SvenDowideit)
Merge pull request #3817 from philips/CONTRIBUTING-is-just-a-dco

fix(CONTRIBUTING): Developer Certificate of Origin w/o Grant
update warning about local dns resolvers

This changes the local DNS resolver warning to explain what the
warning is about and why the default external DNS server is used.

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
Remove verbose logging for non errors
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Merge pull request #4155 from crosbymichael/remove-reflink

Remove unused reflink files
Merge pull request #4171 from SvenDowideit/4061-remote-api-warning

change the -H TCP / docker group warning to not reference a resolved issue
Merge pull request #4188 from unclejack/update_dns_resolver_warning

update warning about local dns resolvers
Merge pull request #4153 from crosbymichael/move-proxy

Move proxy into pkg
Move job register into servapi
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Revert "Merge pull request #4151 from crosbymichael/improve-404-client-message"

This reverts commit 6dd1bb9eb08dc144bc172b0052df7c3904896e56, reversing
changes made to 23aec9d7fcaa72db026c042046102b381e2e9d27.

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)