Revisions and edits based on feedback.

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)
Merge pull request #8178 from SvenDowideit/systemd-example-moved

That Systemd example URL isn't there anymore
Merge pull request #8157 from SvenDowideit/sshd-pam-fix

Fix for user kicked off after login on some hosts
Merge pull request #8197 from fredlf/adding_official-repo-guidelines

Docs for Official Repo release
Rewrite TestBuildForceRm to not use fixtures

Signed-off-by: Alexandr Morozov <lk4d4@docker.com>
Rewrite TestBuildHistory to not use fixtures

Signed-off-by: Alexandr Morozov <lk4d4@docker.com>
Fix code example formatting in best-practices article

Signed-off-by: Lajos Papp <lajos.papp@sequenceiq.com>
Rewrite TestBuildRm to not use fixtures

Signed-off-by: Alexandr Morozov <lk4d4@docker.com>
Rewrite TestBuildWithInaccessibleFilesInContext to not use fixtures

Signed-off-by: Alexandr Morozov <lk4d4@docker.com>
Rewrite TestContextTar tests to not use fixtures

Signed-off-by: Alexandr Morozov <lk4d4@docker.com>
Merge pull request #8182 from LK4D4/logjson_benchmark

pkg/logjson benchmark and test
Fix quoting of TESTFLAGS in devenvironment.md

Copy and pasting the example should now work, rather than TESTFLAGS being silently ignored.
Merge pull request #8173 from crosbymichael/update-mem-limit

Update memory limit for container
IPAllocator: Ensure the allocated IPs are within network range.

Since it is possible to request a specific IP, IPAllocator has to verify
that the request is within boundaries.

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>
Merge pull request #8200 from aluzzardi/f-ipallocator-check-range

IPAllocator: Ensure the allocated IPs are within network range.
Merge pull request #8207 from LK4D4/rewrite_more_fixtures_test

Rewrite more fixtures test to not use fixtures.
Replace get.docker.io -> get.docker.com and test.docker.io -> test.docker.com

Signed-off-by: Tibor Vass <teabee89@gmail.com>
Merge pull request #8195 from tiborvass/migrate-get.docker.io

Replace get.docker.io -> get.docker.com and test.docker.io -> test.docker.com
Merge pull request #8212 from hugoduncan/patch-1

Fix quoting of TESTFLAGS in devenvironment.md
Merge pull request #8205 from sequenceiq/master

Fix code example formatting in best-practices article