use tune2fs to disable ext4 mount counts and mount intervals
Signed-off-by: Marc Tamsky <mtamsky@gmail.com> (github: tamsky)
Document how to pass ENV vars to the user's shell

As this is a somewhat common question.

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@docker.com> (github: SvenDowideit)
Allow /etc/hosts and /etc/resolv.conf to be updated both outside and
inside the container.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
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
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
Merge pull request #8044 from brahmaroutu/container_copy_6107

Change the copy command Content-Type header to x-tar
Merge pull request #8005 from SvenDowideit/document-sshd-env-vars

Document how to pass ENV vars to the user's shell