Fix duplicate iptables rules

If iptables version is < 1.4.11, try to delete the rule vs. checking if it exists. Fixes #6831.

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jfrazelle@users.noreply.github.com> (github: jfrazelle)
Add an option to disable IP masquerading

For the cases where --bip option is used it is sometimes best to disable
IP masquerading as the provided bridge IP range may be routable.

Signed-off-by: Eugene Yakubovich <eugene.yakubovich@coreos.com>
Add a little description of the image tarball format.

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@docker.com> (github: SvenDowideit)
Initialize execStore while restoring a container from checkpoint.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
test for panic on daemon restart

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jess@docker.com> (github: jfrazelle)
Merge pull request #8115 from vishh/exec_panic_fix

Initialize execStore while restoring a container from checkpoint.
'an file' -> 'a file' grammar fix

Signed-off-by: Albert Callarisa Roca <albert@acroca.com>
Merge pull request #8111 from acroca/master

Grammar fix
Merge pull request #8061 from SvenDowideit/document-image-tarball-format

Add a little description of the image tarball format.
Merge pull request #6950 from jfrazelle/6831-check-flag-centos6.5

Fix duplicate iptables rules
Merge pull request #7694 from eyakubovich/master

Add an option to disable IP masquerading