Add a best practice to reduce cache invalidations

inspired by https://github.com/docker-training/docker-fundamentals/pull/206

Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au>
merged conflicting commits

Signed-off-by: Nathan Hsieh <hsieh.nathan@gmail.com>
Squashed commit of the following:

commit 3f9e9185fe7ee51f2fe55f0fc0d4fffdc4f289dc
Author: Nathan Hsieh <hsieh.nathan@gmail.com>
Date:   Mon Oct 6 10:57:35 2014 -0700

    changed the title of back buttons

commit f86934424e85931ec293e711ceaa93ee920828fb
Author: Nathan Hsieh <hsieh.nathan@gmail.com>
Date:   Mon Oct 6 10:53:15 2014 -0700

    Finished level 2, refactored tests

commit 8f502bce05293cccaf200b69ce5f5826eee72484
Author: Nathan Hsieh <hsieh.nathan@gmail.com>
Date:   Mon Oct 6 08:52:37 2014 -0700

    stylized better and added level 2

commit 07b2276b346c34c0cc0faa57500c40e120e77888
Author: Nathan Hsieh <hsieh.nathan@gmail.com>
Date:   Fri Oct 3 18:17:29 2014 -0700

    broke tutorial tests styles

commit 35d84147dc2f65b0ffeea5faf304add903219b1e
Author: Nathan Hsieh <hsieh.nathan@gmail.com>
Date:   Fri Oct 3 17:23:48 2014 -0700

    structured test level1 md file

commit 808d01b0d55d67eb1017f290a29da6c7d38565f2
Author: Nathan Hsieh <hsieh.nathan@gmail.com>
Date:   Fri Oct 3 17:15:46 2014 -0700

    Modified files and integrated tutorial through new page

commit 0f0093f2882489c3eeb6f8870f2b8aa64dc939a3
Author: Nathan Hsieh <hsieh.nathan@gmail.com>
Date:   Thu Oct 2 14:34:44 2014 -0700

    more refactoring

commit 5a9b98e55ebd455ccf2c0ced20f984545a0b6d71
Author: Nathan Hsieh <hsieh.nathan@gmail.com>
Date:   Thu Oct 2 11:46:58 2014 -0700

    clean js code

commit af3bbd8d5e1dffdaa1780f83b909ff566906e513
Author: Nathan Hsieh <hsieh.nathan@gmail.com>
Date:   Thu Oct 2 11:26:39 2014 -0700

    level 1 cleanup

commit c4852a7766ab4fbd978d65c8352ace05eb427ef5
Author: Nathan Hsieh <hsieh.nathan@gmail.com>
Date:   Thu Oct 2 11:20:17 2014 -0700

    fixed up fill-in level1

commit 7f02d80942549dec9c05f784b777fcb32d5bb81b
Author: Nathan Hsieh <hsieh.nathan@gmail.com>
Date:   Wed Oct 1 17:45:42 2014 -0700

    added dockerfile tut, stylized lesson1 Questions

Signed-off-by: Nathan Hsieh <hsieh.nathan@gmail.com>
added fixes to address comments

Signed-off-by: Nathan Hsieh <hsieh.nathan@gmail.com>
Merge pull request #8461 from SvenDowideit/copy-specific-files-from-context

Add a best practice to reduce cache invalidations
Merge pull request #8419 from nhsiehgit/dockerfiletut

Dockerfiletut
Allow IPC namespace to be shared between containers or with the host

Some workloads rely on IPC for communications with other processes.  We
would like to split workloads between two container but still allow them
to communicate though shared IPC.

This patch mimics the --net code to allow --ipc=host to not split off
the IPC Namespace.  ipc=container:CONTAINERID to share ipc between containers

If you share IPC between containers, then you need to make sure SELinux labels
match.

Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: rhatdan)