Feature/add power consumption and place of collocation

- new column in asset model 'power_consumption'
- new column in asset model 'place_of_collocation'
- new flag in assetcategory named 'is_power_consumption'
- new flag in assetcategory named 'is_place_of_collocation'
- use DependencyForm
- create common class for BaseAddAssetForm and BaseEditAssetForm with dependencies method
- update tests
- update api_pricing
- new schemamigration