Add support for new distribution status in rosdistro distribution files

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We have explicitly listed current and past rosdistros in the config.

With http://www.ros.org/reps/rep-0153.html there is now a distribution status with prerelease active and end-of-life which could be used for rendering them.

And instead of explicitly listing them we could provide a whitelist or blacklist which would overlay from the official listings in the rosdistro.