This patch adds a new method for deleting all inventories for a
resource provider: DELETE /resource-providers/{uuid}/inventories
Return codes:
204 NoContent on success
404 NotFound if the resource provider does not exist
405 MethodNotAllowed if a microversion is specified that is before
this change (1.5)
409 Conflict if inventory in use or if some other request concurrently
updates this resource provider
Change-Id: I1ecb12c888f873e8330367c8411d5a2ef0458495
Implements: bp delete-inventories-placement-api