Pause/freeze containers during commit

Initiates a pause before committing a container,
adds a pause option to the commit command, defaulting to 'true'.

Fixes bug: #6267
Fixes bug: #3675

Docker-DCO-1.1-Signed-off-by: Eric Windisch <ewindisch@docker.com> (github: ewindisch)
Upstream-commit: 3775c33ab9
Component: cli

components/cli/docs/sources/reference/commandline/cli.md

@@ -337,6 +337,7 @@ schema.
 
       -a, --author=""     Author (e.g., "John Hannibal Smith <hannibal@a-team.com>")
       -m, --message=""    Commit message
+      -p, --pause=true    Pause container during commit
 
 It can be useful to commit a container's file changes or settings into a
 new image. This allows you debug a container by running an interactive
@@ -344,6 +345,11 @@ shell, or to export a working dataset to another server. Generally, it
 is better to use Dockerfiles to manage your images in a documented and
 maintainable way.
 
+By default, the container being committed and its processes will be paused
+during the process of committing the image. This reduces the likelihood of
+encountering data corruption during the process of creating the commit.
+If this behavior is undesired, set the 'p' option to false.
+
 ### Commit an existing container
 
     $ sudo docker ps