* removes any bits related to loading classic drivers from
the drivers factory code
* removes exceptions that only happen when classic drivers
can be loaded
* removes the BaseDriver, moves the useful functionality to
the BareDriver class
* /v1/drivers/?type=classic now always returns an empty list
* removes the migration updating classic drivers to hardware
types
The documentation will be updated separately.
Change-Id: I8ee58dfade87ae2a2544c5dcc27702c069f5089d
53e7baef42