Make Identity v2 service clients as available  module

All Identity v2 service clients are in lib now and
lib/services/client.py->ServiceClients should register
those service clients automatically and make them available for
external usage.

This patch remove 'identity.v2' from _tempest_internal_modules
and add in tempest_modules.

Change-Id: I4142bc9a451edccaa70d2311e0fe27ec20adc972
1 file changed