0.9.0 feature: docker.io containers support

[Bohuslav Kabrda]

Hi all,
apart from dependencies versioning, there is another big feature I'd like to implement - working with docker.io containers. I tried to sum this up at issue tracker [1]. What we need to do:

* Find out what is the optimal development workflow with docker.io containers.
* Add a CommandRunner class that would create these containers.
* Document this feature.
* Actually use this in default assistant set.

Maybe we should modify package managers so that we can reuse them for installing dependencies into containers - but I'm not sure about this. A second option would be to just provide dockerfiles for certain projects, but that would mean that we can't modify the containers/images... Do we want to modify these, too? :)

Thanks for all your comments/opinions/suggestions.
Slavek.

[1] https://github.com/bkabrda/devassistant/issues/143