* Add "testable" field to the Part model
- Default = False
- Determines whether a particular part can have tests defined against it
* Adds data migration to set default 'testable' state
* Update part serializers
* CUI: Update table filters
* PUI: Update tables and filters
* CUI: Update part detail page
* PUI: Update part detail page
* Update CUI
* Update build pages
* Update BuildLine serializer
* Bump API version
* Update docs
* Add 'testable' to fieldset