Fix error paring null JSON - Issue7941

Closes #7941

Treat a null in JSON, when reading the config of a container, as if the
property was never included.  W/o this fix the null would be saved in the
property as a string with a value of "null".

Signed-off-by: Doug Davis <dug@us.ibm.com>
Remove nameserver 127.0.0.1 line rather then dumping resolv.conf

We have a bug report complaining about docker dumping the contents of the
hosts resolv.conf if it container 127.0.0.1.  They asked that instead
of dropping the file altogether, that we just remove the line.

This patch removes the 127.0.0.1 lines, if they exist and then
checks if any nameserver lines exist.

Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: rhatdan)
Replace utils.CheckLocalDns with bytes.Contains line

Since RemoveLocalDns patch will  remove all localhost entries
from resolv.conf we no longer need anything more then
!bytes.Contains(resolvConf, []byte("nameserver")

To check for no nameserver entry in dns config.

Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: rhatdan)
Merge pull request #8047 from rhatdan/RemoveLocalDns

Remove nameserver 127.0.0.1 line rather then dumping resolv.conf
builder: Fix CMD to inject /bin/sh -c when provided with a non-json value.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Merge pull request #8284 from erikh/fix_cmd_again

builder: Fix CMD to inject /bin/sh -c when provided with a non-json value
Merge pull request #8273 from duglin/Issue7941

Fix error paring null JSON - Issue7941
Fixes the new testcase for PR #8230

This new version makes sure that the same context is used for the two
builds run in the test.  If you don't use the same build then about 1/2 the
time the file copied into the container will look like a different file,
probably due to timestamp differences.  But reusing the same context we
re-use the same file on disk and therefore avoid the change in timestamps,
and we use the cache on the 2nd build.

Signed-off-by: Doug Davis <dug@us.ibm.com>
improve docs for Gentoo Linux installation

Changes summary:
    * Added available USE flags table(description included).
    * Added some tips regarding the use of docker in the Gentoo environment.
    * Sorted out docker installation ways.
    * Added information about the newly created Gentoo Docker team.
    * Misc improvements

Signed-off-by: Pavlos Ratis <dastergon@gentoo.org>
Merge pull request #8210 from dastergon/improve_gentoodoc

improve docs for Gentoo Linux installation
Merge pull request #8289 from duglin/FixTestcaseFor8230

Fixes the new testcase for PR #8230
Remove the graphdb (links). Replace with code and json structure.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Stubbing out links jobs and commandline

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
`docker links add` feature.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Test for `docker links add`

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
links: Fixups and remove support for index

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Remove UI, API, and Jobs.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
More tests for add/remove.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Small touchups for the container index, fix an issue where create/start
were linking twice.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Fix tests in etchosts package, plus additional tests for new
functionality.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)