Merged
requested to merge feature/import_gem_taxonomy_based_building_classes into refactoring_to_sql
Created a new table BuildingClassesMapping
and stored all the GEM taxonomy-based building classes mapped to the building exposure attributes (i.e. building_type_id, construction_material_id, story_number_id).
This mapping table is later used to map the building exposure attributes in the final BuildingAsset table.