Merge pull request #8010 from LK4D4/fix_ps_s_hang_#7999

Fix ps -s hang
The default name of the bridge created is called 'docker0'.
docs: shrink images

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
docs: change kernel version requirement

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
Merge pull request #7698 from tamsky/tune2fs_base_filesystem

use tune2fs to disable ext4 mount counts and mount intervals
clean up the context when a build fails

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
Merge pull request #8038 from unclejack/failed_build_context_cleanup

clean up the context when a build fails
Adding Exec method to native execdriver.
Modified Attach() method to support docker exec.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Adding support for docker exec in daemon.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Adding 'exec' command to remote API and CLI.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Import nsenter in docker.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Fix bug in attach handling for docker exec. Add docs for 'docker exec' feature.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Update cli.md to include 'docker exec' feature.
Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Adding integration tests for docker exec feature.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Address review comments.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Removing 'exec' feature from the CLI until the docker daemon supports resizing of
tty sessions for exec'ed commands.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Change the copy command Content-Type header to x-tar
Addresses #6107

Signed-off-by: Srini Brahmaroutu <srbrahma@us.ibm.com>
Merge pull request #8020 from erikh/rewrite_hosts_files

Links v2: Mutable network files
tarsum: include xattr headers in to the checksum

this is to enhance the tarsum algorithm, but _MUST_ be done in lock step
with the same for docker-registry. (PR will be cited)

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)
Merge pull request #8044 from brahmaroutu/container_copy_6107

Change the copy command Content-Type header to x-tar