Handling of tww_app

[cymed]

In the future, tww_app ought to be dropped and re-created on model updates (see #128). This requires some adaptations:

• [x] in create views, add a psycopg2 statement to drop tww_app
• [ ] Add a point in the developer's guide to never store any tables with ordinary data in txx_app (see #85 for a bad examples)
• [x] When dropping and re-creating tww_app, the default grants for tww_app need to be set differently

Furthermore, the current code of create_views.py only works inside the dockerised environment, as the relations to the plain sql views such as /app/view/vw_dictionary_value_list.sql are absolute. This poses problems for people using datamodel extensions who would like to re-create the views dynamically from their environments.

@ponceta Opinions?

[ponceta]

This is directly on the roadmap to release management and production for TEKSI wastewater.