Csv import changes

Added tests & updated factories.
Fixed data importer bugs:
- importing barcode with value ''
- importing data for fields:
- LicenceType,
- Service,
- BudgetInfo,
- ServiceCatalog,
- DeviceEnvironment,
- AssetOwner
- AttributeError for category field (api_ralph)

Data importer improvments:
- getting data from field of types: BooleanField, DateTime, Date
- added delimiter guessing
- col 'id' in import-update can by anywhere (before only first col)
- adding new assets tries to match device by this chain: barcode then sn