Reworks Chassis validations

This makes use of complex types validations of WSME that now works.

Change-Id: I5cd46d5c2caeb3f3c4cd1ef90448e7fd3c81404d
Closes-Bug: #1223847
Merge "Reworks Chassis validations"
Improve method to get list of active conductors

To facilitate the consistent hash ring, we must know not only what
conductors are active, but also which driver(s) each active conductor
supports. This patch renames list_active_conductor_drivers to
get_active_driver_dict and changes the return value to be a dict,
mapping drivers to the set of hosts which support them.

blueprint instance-mapping-by-consistent-hash

Change-Id: Ie327aa7d9207f6f5da1380631dbbc431dfd7e218
GET /drivers to show a list of active conductors

Make the GET /drivers return not only the name of the drivers but also
a list of active conductors that supports each driver.

Change-Id: I9646b84e266665e23c62ca11cb58c35cf2803c10
Merge "Improve method to get list of active conductors"
Merge "GET /drivers to show a list of active conductors"