switch to built images instead of self-built #12
Description
At present we are building images on-site. A slightly more efficient process would be to build multiple images. THis could be done in 2 repositories, one for the (single) Wordpress image, and another for the (multiple) node images. Understrap uses system gulp, so needs to have gulp installed; both foundationpress and jointswp use local gulp via npm, and so maybe have conflicts w/ the global gulp (but maybe not, if they're run right, via npm). So, should investigate whether can have a single image. New run scripts have eliminated all static elements so they could perhaps be universalized.
See the docker automated build docs for more info on building.