Open source Instructure base docker images

Updating an image

The language base images along with their web server (passenger) counterparts are all generated using a template system. To make changes change the files in the respective template directory then run rake to propagate the changes to each version of the build directory. Parameters for building each templated directory are supplied by the manifest file found in the project directory. Each object supplied in the versions object corresponds to a version directory in the respective language. This object is merged with the defaults object along with version and generation_message keys are supplied to any template files specified in the manifest.