Refactoring to allow addition of NetApp FibreChannel drivers

NetApp's five Cinder drivers have been in continuous development
for nearly 3 years, and it is now necessary to do some house-
cleaning.  This commit splits long files that contain multiple
classes, fixes the class hierarchies to enable subclassing
different driver classes (ISCSIDriver, FibreChannelDriver),
and renames classes.  It also begins the process of moving
unit test files into a matching hierarchy in the "tests" tree.

Implements blueprint netapp-cinder-driver-refactoring-phase-1
Change-Id: I9b067a8322a676c4c95d5045cb2e78979be9ba5b
Merge "Refactoring to allow addition of NetApp FibreChannel drivers"