Risk exposure Importer from nrml to db needed

[Muharem Hrnjadovic]

Now that we have the risk exposure model tables in the schema we need the logic to populate them from nrml files

[Mattia Barbon (mattia.barbon)]

See also https://bugs.launchpad.net/openquake/+bug/812288

[Mattia Barbon (mattia.barbon)]

Double check:

- exposure_model.description is the gml:description child of exposureList
- assetDescription is discarded, so there is no way to export back the original model

[Mattia Barbon (mattia.barbon)]

Pull request https://github.com/gem/openquake/pull/373

[Mattia Barbon (mattia.barbon)]

Closed the pull request for now (we will likely switch so Django ORM and the pull request is all SQLAlchemy code); the branch might still be useful as a starting point.

[Mattia Barbon (mattia.barbon)]

Pull request https://github.com/gem/openquake/pull/436

[Mattia Barbon (mattia.barbon)]

Vulnerability function reference are ambiguous by themselves.

Might need a vulnerability model reference to be added to the NRML file.

[Mattia Barbon (mattia.barbon)]

Pull request https://github.com/gem/openquake/pull/480