Enhancements to datasets

- Add energy cost fields to profiles.
- Update datasets API
- Change the pipeline and calculations.
- Fix bug in padding
- Tidy up test ns.
- Use dirty dates for datasets.

Needs database migration: cql/20141007_datasets.cql

Fixes #362 
Fixes #359 
Fixes #360 
should this function go into a kixi.hecuba.number ? Similar to kixi.hecuba.time?