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
Revert "Change content-type for json stream to application/x-json-stream."

This reverts commit 10ab2089ce189d5bea3f7aaac3b5081471309478.

Conflicts:
	api/client/utils.go
	docs/sources/reference/api/docker_remote_api.md

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jess@docker.com> (github: jfrazelle)
Revert "Fix line delimited JSON response"

This reverts commit d2f75a3040e72562ffa825d5c3efa7004af2640a.

Conflicts:
	integration-cli/docker_api_events_test.go

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jess@docker.com> (github: jfrazelle)
Add -E flag to sudo (fixes #8494)

Docker-DCO-1.1-Signed-off-by: Jérôme Petazzoni <jerome@docker.com> (github: jpetazzo)
Merge pull request #8482 from jfrazelle/8481-content-type-bump-v

Revert #8101 and #7886 (content-type:x-json-stream/line delimited json)
Merge pull request #8495 from jpetazzo/8494-fix-debian-frontend-in-getdockercom-script

Add -E flag to sudo (fixes #8494)
Update desktop integration examples to be more up to date.
Chromium > Iceweasel and cool new gparted example.

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jess@docker.com> (github: jfrazelle)