Provide a method to enforce installation of an image

[dahaic]

Hello, I'd like to present you scenario we face with openscap (scanner image). For the image to work, it is necessary to be installed by running atomic install rhel7/openscap. But actually it won't fail when installation is not performed, it will just behave in different way. So we have to track somehow that it is not installed (which is not easy from the perspective of the container) and explain it to user. (Also in our case, we don't need to call install with every update, but it might happen, occasionally that it is necessary.)

It seems that atomic is in better position to handle this requirement than having every container make its own check and its own error message to the user. Is it something you can add to the project?