Docker-map

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* Added evaluation of ``.dockerignore`` files.
* Several bugfixes from `0.6.6b1`.

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* Added arguments to set additional image tags after build.
* Added ``default_tag`` property to container maps.
* Minor refactoring. Possibly breaks compatibility in custom policy implementations:

* ``dockermap.map.policy.cache.CachedImages.reset_latest`` has been renamed to
:meth:`~dockermap.map.policy.cache.CachedImages.reset_updated`.
* :meth:`~dockermap.map.policy.cache.CachedImages.ensure_image` argument ``pull_latest`` has been renamed to
``pull``.
* ``dockermap.map.policy.update.ContainerUpdateMixin.pull_latest`` has been renamed to
:attr:`~dockermap.map.policy.update.ContainerUpdateMixin.pull_before_update`.
* ``dockermap.map.policy.base.BasePolicy.iname`` has been renamed to
:meth:`~dockermap.map.policy.base.BasePolicy.image_name` and changed order of arguments for allowing defaults.

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* Better support for IPv6 addresses. Added ``ipv6`` flag to port bindings and ``interfaces_ipv6`` property to client
configuration.
* Command elements are converted into strings so that Dockerfiles with a numeric command line element do not raise
errors.

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* Fixed exception on stopping a container configuration when the container does not exist.

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* Improved fixed behavior when merging container maps and embedded container configurations. Can also be used for
creating copies.
* Added ``stop_timeout`` argument to ``remove_all_containers``.
* Fixed transfer of configuration variables into client instance.

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* Added ``stop_signal`` for customizing the signal that is used for shutting down or restarting containers.
* Minor changes in docs and log messages.
* Fixed image cache update with multiple tags.
* Bugfix in Dockerfile module.