STATIC_ROOT moved to djpl.settings.STATIC_ROOT = None; STATIC_ROOT is refined by djpl-product-data or djpl-container-data;
added productcontext.py for generating a feature-specific product context; method should be refined by each feature bringing own product context stuff;
MEDIA_ROOT initialized as None; djpl-data features now refine MEDIA_ROOT and STATIC_ROOT;
DATABASES initialized as None; djpl-sqlite or djpl-postgres now refine DATABASES
adjusted generate_context_json task to work with productcontext.get_context() instead of context_template from feature.json