Geonode integration

Preliminary work in the context of https://blueprints.launchpad.net/oq-platform/+spec/icebox-geonoe

Summary of changes:

1) removed HTML form generation capabilities. OQ-Engine-Server will just provide a RESTful JSON API
2) added db-to-db data migration. Once that a calculation on the oq-engine cluster has completed, oq-engine-server will perform a COPY FROM / COPY TO data transfer between the database of oq-engine and the one on the oq-platform.