Add pull_latest option

This option will cause ansible to pull the latest image before running
a new container.
Add restart_policy to docker module
Docker: Add support for insecure registry

For security reasons, docker-py will only fetch images from HTTPS, not plain HTTP
based registries.

This change adds a insecure_registry flag to the docker module to allow
it to fetch images also via insecure HTTP.
Merge branch 'devel' into add-insecure-registry