* Adds new fields to the SupplierPart model:
- available
- availability_updated
* Allow availability_updated field to be blank
* Revert "Remove stat context variables"
This reverts commit 0989c308d0.
* Increment API version
* Adds availability information to the SupplierPart API serializer
- If the 'available' field is updated, the current date is added to the availability_updated field
* Add 'available' field to SupplierPart table
* More JS refactoring
* Add unit testing for specifying availability via the API
* Display availability data on the SupplierPart detail page
* Add ability to set 'available' quantity from the SupplierPart detail page
* Revert "Revert "Remove stat context variables""
This reverts commit 3f98037f79.