Return correct exit code upon signal + SIGQUIT now quits without cleanup

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume@charmes.net> (github: creack)
Fix configuration test for MKNOD
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Allow force sigint and allow sigquit after sigint

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume@charmes.net> (github: creack)
Fix --volumes-from mount failure

As explained in https://github.com/dotcloud/docker/issues/4979
--volumes-from fails with ENOFILE errors.

This is because the code tries to look at the "from" volume without
ensuring that it is mounted yet. We fix this by mounting the containers
before stating in it.

Also includes a regression test.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
Merge pull request #4989 from alexlarsson/fix-volumes-from

Fix --volumes-from mount failure
Allow non-privileged containers to create device nodes.

Such nodes could already be created by importing a tarball to a container; now
they can be created from within the container itself.

This gives non-privileged containers the mknod kernel capability, and modifies
their cgroup settings to allow creation of *any* node, not just whitelisted
ones.  Use of such nodes is still controlled by the existing cgroup whitelist.

Docker-DCO-1.1-Signed-off-by: Kevin Wallace <kevin@pentabarf.net> (github: kevinwallace)
Add myself to AUTHORS.

Docker-DCO-1.1-Signed-off-by: Kevin Wallace <kevin@pentabarf.net> (github: kevinwallace)
Merge pull request #4980 from creack/update_signal_management

Return correct exit code upon signal + SIGQUIT now quits without cleanup
Merge pull request #4992 from crosbymichael/fix-mknod-test

Fix configuration test for MKNOD