Vulnerability - Some functions in the platform have the GEM taxonomy string wrong

[CatalinaYepes]

The GEM taxonomy string specified in some curves is not correct, specially in the curves from HAZUS (these curves were added before implementing the validation).

See https://platform.openquake.org/vulnerability/view/469/

[nastasi-oq]

Each curve now has proper taxonomy on production and staging.
There are 2 issues not yet released:

• Bug when populating a taxonomy with irregularity oq-platform-taxtweb#8 (committed and not released)
• Vulnerability - not allow empty taxonomy when save a curve. #611 (investigating)